I just noticed it last week that Windows Malicious Software Removal Tool failed to install and when I checked the update history, it had already been like this since August 2016. Why is this so? How can I troubleshoot it. Thanks a lot.
If you had no anti-virus application installed or the subscription had expired when the machine first got infectedand/or your subscription has since expired and/or the machine's not been kept fully-patched at Windows Update, don't waste your time with any of the below: Format & reinstall Windows. A Repair Install will NOT help!
Microsoft PCSafety provides home users (only) with no-charge support in dealing with malware infections such as viruses, spyware (including unwanted software), and adware.
1. Download/run the MSRT manually
2. Run the FULL scan, not the QUICK scan! You may need to download the MSRT on a non-infected machine, then transfer MRT.EXE to the infected machine and rename it to SCAN.EXE before running it.