High disk usage on startup can occur when there are too many programs or processes running simultaneously, resulting in a bottleneck and causing the system to slow down. This can be caused by a variety of factors, including malware and viruses, system errors, disk errors, startup programs, and hardware issues.
Image: 100% Disk Usage on PC Startup
Here is a list of all the possible causes of high disk usage on startup:
Malware and viruses: Malware and viruses can cause high disk usage by creating unnecessary processes that run in the background.
System errors: System errors can also cause high disk usage. These errors can be caused by corrupt system files, software conflicts, or other issues.
Disk errors: Disk errors can cause high disk usage by preventing the system from accessing data stored on the hard drive.
Startup programs: Too many startup programs can cause high disk usage on startup. These programs are launched automatically when the system boots up, which can put a strain on the system’s resources.
Programs with high CPU usage: Some programs may use a large amount of CPU resources, which can cause high disk usage.
Outdated hardware or drivers: Using outdated hardware or drivers can cause high disk usage on startup. Updating to the latest version can help improve system performance and resolve high disk usage issues.
It is important to fix high disk usage on startup as it can significantly affect the performance of your system, causing it to run slow and become unresponsive. If left unchecked, it can lead to longer startup times and potential data loss.
To check if you’re computer has a high disk usage, you can do this:
Open the Task Manager by pressing the Ctrl + Shift + Esc keys on your keyboard simultaneously.
In the Task Manager, go to the Performance tab and look for the Disk section. If you see that the disk usage is consistently at 100%, it means that there is an issue with your system that is causing the high disk usage.
If you are experiencing high disk usage on your computer, we recommend following the steps outlined in the guide below to troubleshoot and resolve the issue.
How to Fix 100% Disk Usage on PC Startup
This guide may appear overwhelming due to the number of steps and numerous programs that are being used. We have only written it this way to provide clear, detailed, and easy-to-understand instructions that anyone can use to fix their computer. Please perform all the steps in the correct order. If you have any questions or doubts at any point, stop and ask for our assistance.
To fix the high disk usage on PC startup, follow these steps:
STEP 1: Check your computer for malware and viruses
In this first step, we will check your computer for malicious programs that might cause high disk usage. To do this we will manually search and uninstall malicious programs, remove malicious browser extensions, and finally run an anti-malware scan.
1. Uninstall malicious programs
First, we will manually check if any unknown or malicious programs are installed on the computer. Sometimes adware and browser hijackers can have a usable Uninstall entry that can be used to remove them.
Windows 11Windows 10Windows 8Windows 7
Open the Settings app
Press Windows + I on your keyboard to open Settings. Alternatively, right-click the Start button and select “Settings” from the menu.
Go to “Apps & Features”
In the Settings window, click “Apps” in the sidebar, then select “Apps & Features“.
Find and uninstall the malicious program
Scroll through the list of installed apps and look for anything suspicious — a program you don’t remember installing, or one with a strange or generic name. Quick tip: click “Sort by” and choose “Install date“. Malware is usually one of the most recently installed programs, so it will appear near the top.
When you find the malicious program, click the three dots next to it and select “Uninstall“.
Didn’t find any suspicious programs? That’s fine — not all infections install visible apps. Just continue with the next step in this guide.
Complete the uninstall
Confirm by clicking Uninstall in the message box, then follow the remaining prompts. Read each prompt carefully — some malicious programs use confusing wording or pre-ticked boxes hoping you’ll click through without looking.
Open the Settings app
Press Windows + I on your keyboard to open Settings. Alternatively, click the Start button on the taskbar and select “Settings” (the gear icon).
Click on “Apps”
In the “Windows Settings” window, click “Apps“. The “Apps & Features” section should open by default — if it doesn’t, select it from the list on the left.
Find and uninstall the malicious program
Scroll through the list of installed apps and look for anything suspicious — a program you don’t remember installing, or one with a strange or generic name. Quick tip: click “Sort by” and choose “Install date“. Malware is usually one of the most recently installed programs, so it will appear near the top.
When you find the malicious program, click on it and select “Uninstall“.
Didn’t find any suspicious programs? That’s fine — not all infections install visible apps. Just continue with the next step in this guide.
Complete the uninstall
Confirm by clicking Uninstall in the message box, then follow the remaining prompts. Read each prompt carefully — some malicious programs use confusing wording or pre-ticked boxes hoping you’ll click through without looking.
Open “Programs and Features”
Right-click the Start button in the taskbar, then select “Programs and Features“. This takes you straight to the list of installed programs.
Find and uninstall the malicious program
Scroll through the list of installed programs and look for anything suspicious — a program you don’t remember installing, or one with a strange or generic name. Click to highlight it, then click the “Uninstall” button.
Didn’t find any suspicious programs? That’s fine — not all infections install visible apps. Just continue with the next step in this guide.
Complete the uninstall
Confirm by clicking Yes in the message box, then follow the remaining prompts. Read each prompt carefully — some malicious programs use confusing wording or pre-ticked boxes hoping you’ll click through without looking.
Open the Control Panel
Click the “Start” button, then click “Control Panel“.
Click on “Uninstall a Program”
In the Control Panel, click “Uninstall a Program” under the Programs category.
Find and uninstall the malicious program
Scroll through the list of installed programs and look for anything suspicious — a program you don’t remember installing, or one with a strange or generic name. Click to highlight it, then click the “Uninstall” button.
Didn’t find any suspicious programs? That’s fine — not all infections install visible apps. Just continue with the next step in this guide.
Complete the uninstall
Confirm by clicking Yes in the message box, then follow the remaining prompts. Read each prompt carefully — some malicious programs use confusing wording or pre-ticked boxes hoping you’ll click through without looking.
Is a stubborn program refusing to uninstall? Use Revo Uninstaller to force-remove it completely, including leftover files and registry entries.
With the malicious programs removed, you’re ready for the next step in this guide.
2. Clean up your browser
Next, we will remove spam notifications, malicious extensions, and change to default any settings that might have been changed by malware. Please note that this method will remove all extensions, toolbars, and other customizations but will leave your bookmarks and favorites intact. For each browser that you have installed on your computer, please click on the browsers tab below and follow the displayed steps to reset that browser.
ChromeFirefoxMicrosoft EdgeInternet Explorer
Reset Chrome for Windows to default settings
We will now reset your Chrome browser settings to their original defaults. This will reset your startup page, new tab page, search engine, and pinned tabs. It will also disable all extensions and clear temporary data like cookies. Your favorites, history, and saved passwords will not be cleared.
Open the Chrome menu
In the top-right corner of Chrome, click the three-dot (⋮) icon to open the menu.
Go to Settings
From the menu, select Settings.
Select “Reset settings”
In the left sidebar, scroll down and click Reset settings.
Choose “Restore settings to their original defaults”
Click Restore settings to their original defaults.
Confirm the reset
In the dialog that appears, click Reset settings. This restores your homepage, search engine, new tab page, and pinned tabs to default, disables all extensions, and clears temporary site data — undoing the changes the malware made.
Don’t worry: your bookmarks, history, and saved passwords are safe and will not be deleted.
Reset Firefox for Windows to default settings
We will now reset your Firefox browser settings to their default. The reset feature fixes many issues by restoring Firefox to its factory default state while saving your essential information like bookmarks, passwords, web form auto-fill information, browsing history, and open tabs.
Open the Firefox menu and click “Help”
Click the three horizontal lines in the top-right corner of Firefox to open the main menu, then select “Help“.
Click “More troubleshooting information”
In the Help menu, click “More troubleshooting information“.
Click “Refresh Firefox”
On the “Troubleshooting Information” page, click the “Refresh Firefox” button in the top-right area of the page.
Confirm the refresh
In the confirmation window, click “Refresh Firefox” again. This removes extensions, themes, and customized settings — the usual hiding places for browser hijackers — while keeping your bookmarks, history, and saved passwords safe.
Click “Finish”
Firefox will close, reset itself to default settings, and reopen with a window listing the information that was restored. Click “Finish” — your Firefox is now clean.
About the “Old Firefox Data” folder: Firefox saves a copy of your old profile on your desktop. If something you need is missing after the reset, you can recover it from this folder. Otherwise, delete the folder — it contains sensitive data like passwords and cookies, and may also still hold the malicious files you just removed.
Reset Microsoft Edge to default settings
We will now reset your Microsoft Edge browser settings to their default. This will reset your startup page, new tab page, search engine, and pinned tabs. It will also disable all extensions and clear temporary data like cookies. Your favorites, history, and saved passwords will not be cleared.
Open the Edge menu and click “Settings”
Click the three dots (…) in the top-right corner of Microsoft Edge to open the main menu, then click “Settings“.
Click “Reset settings”
In the left sidebar, click “Reset settings“.
Click “Restore settings to their default values”
In the main window, click “Restore settings to their default values“.
Confirm by clicking “Reset”
In the confirmation dialog, click “Reset“. This restores your homepage, search engine, new tab page, and startup pages to default, disables all extensions, and clears temporary data like cookies — undoing the changes the malware made.
Don’t worry: your favorites, browsing history, and saved passwords are safe and will not be deleted.
Reset Internet Explorer to default settings
We will now reset your Internet Explorer browser settings to their default. You can reset Internet Explorer settings to return them to the state they were in when Internet Explorer was first installed on your computer.
Go to “Internet Options”.
Open Internet Explorer, click on the gear icon in the upper-right part of your browser, then select “Internet Options“.
Select the “Advanced” tab, then click “Reset”
In the “Internet Options” dialog box, select the “Advanced” tab, then click on the “Reset” button.
Click on “Reset”.
In the “Reset Internet Explorer settings” section, select the “Delete personal settings” checkbox, then click on the “Reset” button.
Click on “Close”.
When Internet Explorer has completed its task, click on the “Close” button in the confirmation dialogue box. Close your browser and then you can open Internet Explorer again.
3. Run a scan with Malwarebytes Anti-Malware Free
Now, we will install Malwarebytes to scan and remove any infections, adware, or potentially unwanted programs that may be present on your computer.
Malwarebytes is one of the most popular and trusted anti-malware tools for Windows — and it’s completely free for removing infections. It catches threats that many antivirus programs miss, including adware, browser hijackers, and trojans. Follow the steps below to scan and clean your PC in just a few minutes.
Download Malwarebytes
Click the button below to download the latest version of Malwarebytes for Windows from the official source. The free version is all you need — it will scan your computer and remove adware, browser hijackers, and other malicious software at no cost.
(The link opens in a new page where your download will start)
Install Malwarebytes
When the download finishes, open your Downloads folder and double-click the MBSetup file. If Windows shows a User Account Control pop-up, click “Yes” to allow the installation.
Follow the On-Screen Prompts to Install Malwarebytes
The setup wizard will walk you through a few quick screens:
Choose where you’re installing the program — “Personal Computer” or “Work Computer” — then click Next.
Malwarebytes will now install on your device. This usually takes under a minute.
When installation is complete, the “Welcome to Malwarebytes” screen will open automatically.
On the final screen, click Open Malwarebytes to launch the program.
Enable “Scan for Rootkits”
Before scanning, turn on rootkit detection so Malwarebytes can find even the most hidden threats. Click the Settings gear icon on the left side of the screen.
In the settings menu, find “Scan for rootkits” and click the toggle so it turns blue.
Done? Click “Dashboard” in the left pane to return to the main screen.
Start the Scan
Click the blue Scan button. Malwarebytes will automatically update its virus database and start checking your computer for malware.
Wait for the Scan to Finish
The scan checks your entire system for browser hijackers and other malicious programs, so it can take several minutes. Feel free to do something else — just check back occasionally to see the progress.
Quarantine the Detected Threats
When the scan is done, you’ll see a list of everything Malwarebytes found — malware, adware, and potentially unwanted programs. Click the “Quarantine” button to remove all of them at once.
Malwarebytes will now remove the malicious files and registry entries and move them safely into quarantine.
Restart Your Computer
Some threats can only be fully removed after a reboot. If Malwarebytes asks you to restart, click Yes. Once you’re logged back in, your PC is clean and you can continue with the next steps in this guide.
4. Double-check for malicious programs with HitmanPro
Finally, we will scan the computer with HitmanPro to ensure that no other malicious programs are installed on your device.
HitmanPro is a second-opinion scanner — it’s designed to catch what your main antivirus might have missed. Instead of relying on a single detection engine, it checks the behavior of files in the locations where malware usually hides. Anything suspicious gets sent to the cloud, where it’s analyzed by two of the best antivirus engines available: Bitdefender and Kaspersky.
Good news: scanning is completely free, with no limits. You only need a license when it’s time to remove what was found — and even then, you can activate a free one-time 30-day trial to clean your PC at no cost. (A full license is $24.95 per year for 1 PC.)
Download HitmanPro
Click the button below to download HitmanPro. Remember — the scan is free, so you have nothing to lose by checking your PC.
When the download finishes, open your Downloads folder and double-click the file: “hitmanpro.exe” on 32-bit Windows, or “hitmanpro_x64.exe” on 64-bit Windows.
If a User Account Control pop-up asks whether HitmanPro can make changes to your device, click “Yes” to continue.
Follow the On-Screen Prompts
On the HitmanPro start screen, click “Next” to begin the system scan. No lengthy setup required — it goes straight to work.
Wait for the Scan to Finish
HitmanPro will now check your computer for malicious programs. This usually takes just a few minutes thanks to its cloud-based scanning.
Review the Results and Click “Next”
When the scan is done, HitmanPro will show you everything it found. Click “Next” to remove the detected threats.
Click “Activate Free License”
To remove the malicious files, click the “Activate free license” button. This starts your free 30-day trial — no payment details needed — and unlocks the full cleanup.
When the removal is complete, HitmanPro will show a summary of everything it cleaned. Click Next, then click Reboot if prompted. If there’s no reboot prompt, just click Close — your PC is clean.
STEP 2: Run the System File Checker (SFC) tool
One potential cause of high disk usage is the presence of system errors. To check for and repair these errors, you can use a tool called the System File Checker (SFC
The SFC tool scans all protected system files on your computer and replaces any files that are corrupt or damaged with a cached copy that is stored in a compressed folder at %WinDir%\System32\dllcache. By running the SFC tool, you can help ensure that your system is functioning properly and fix any issues.
Open Command Prompt as Administrator.
To open the Command Prompt as an administrator in Windows, type “cmd” in the search bar and then right-click on the Command Prompt result and select “Run as administrator” as shown in the image below. A User Account Control (UAC) prompt will appear asking for permission to allow the program to run. Click “Yes”.
Type “sfc /scannow”.
You will now be presented with a black screen called the ‘Administrator: Command Prompt’. On this screen, type “sfc /scannow” to scan for and repair any corrupt system files.
Restart your computer.
Restart your computer if sfc /scannow repaired files. System File Checker may or may not prompt you to restart but even if it doesn’t, you should restart anyway.
Run again sfc /scannow.
Run again sfc /scannow to check if the files were repaired.
STEP 3: Run the Disk Check tool
Another tool that can help identify and fix issues that may be causing high disk usage is the Disk Check tool, also known as “chkdsk.”
This tool checks your hard disk for errors and can fix any issues it finds. To use the Disk Check tool, you will need to open the command prompt and enter the “chkdsk” command followed by the drive letter (e.g., “chkdsk C:”). You can also add the “/f” flag to the command to instruct the tool to fix any errors it finds. By running the Disk Check tool, you can help ensure that your hard disk is functioning properly and fix any issues that may be causing high disk usage.”
Open Command Prompt as Administrator.
To open the Command Prompt as an administrator in Windows, type “cmd” in the search bar and then right-click on the Command Prompt result and select “Run as administrator” as shown in the image below.
A User Account Control (UAC) prompt will appear asking for permission to allow the program to run. Click “Yes”.
Type “chkdsk /f /r”
You will now be presented with a black screen called the ‘Administrator: Command Prompt’. On this screen, type “chkdsk /f /r” to repair any errors on your hard drive.
Restart your computer
The Disk Check tool may require you to restart your computer in order to complete the scan and repair process. Type “Y” and click on Enter, then restart the computer.
A CHKDSK command can take a long time, especially when performed on larger drives. Once it’s done, however, it will present a summary of results including total disk space, byte allocation, and, most importantly, any errors that were found and corrected.
STEP 4: Disable any unnecessary startup programs
Startup programs are applications that automatically launch when you start your computer. While some of these programs may be necessary for your system to function properly, others may be unnecessary and can consume system resources, including disk usage. Disabling unnecessary startup programs can help improve system performance and reduce high disk usage.
Press Ctrl + Shift + Esc on your keyboard to open the Task Manager.
Go to the “Startup” tab (called “Startup apps” on Windows 11). Right-click any program you don’t need launching automatically and select Disable. The “Startup impact” column shows which programs slow down your boot the most — start with the “High” ones.
Not sure what something is? Leave entries from Microsoft, your hardware makers (Intel, NVIDIA, Realtek), and your antivirus enabled — and look up any name you don’t recognize before disabling it. Disabling a startup program doesn’t uninstall it; the program will still work normally when you open it yourself, and you can re-enable it here anytime.
STEP 5: Use Device Manager to find hardware issues
In some cases, high disk usage may be caused by hardware errors or issues with hardware devices connected to your computer. To check for and troubleshoot these types of errors, you can use the Device Manager built-in into Windows.
Open Device Manager.
To access the Device Manager, type “devmgmt.msc” into the search bar on the Start menu and select “Device Manager” from the list of results.
Find hardware devices that work properly.
In the Device Manager, you can view a list of all the hardware devices connected to your computer and check for any errors or issues. If you see a yellow exclamation point next to a device, it may indicate a problem with that device. You can right-click on the device and select “Update driver” or “Troubleshoot” to try and fix any issues.
We hope this guide helps you fix the high disk usage on startup. If you have any other questions or need further assistance, don’t hesitate to start a thread in our forum.
About Stelian
Stelian leverages over a decade of cybersecurity expertise to lead malware analysis and removal, uncover scams, and educate people. His experience provides insightful analysis and valuable perspective.
Didn’t find any suspicious programs? That’s fine — not all infections install visible apps. Just continue with the next step in this guide.
Didn’t find any suspicious programs? That’s fine — not all infections install visible apps. Just continue with the next step in this guide.
