Some antivirus can contribute to the unstability of the system

[viktik]

The protection features ( false positives & proactive protection ), bugs, compatibility issues can cause overall instability of the system as time passes by. The more you install/uninstall applications the messier it gets.

Because antivirus tries to monitor every application & every possible activity, the chance of causing problem gets very high.

It can cause the improper installation of some software. You won't get any warning or messages. But in background antivirus has affected the installation in ways that it becomes unstable or does not function properly. Once this has been done, it cannot be undone. This is most elusive and very hard to tell wrong has been done to the system.

Firewall component may cause network related problems. Unable to upload pictures and other files. Slow internet. Webpages not loading properly. Hanging of software's which uses internet affecting the stability of system. Increased RAM usage by some applications, sometimes causing hanging of system because all the RAM has been used and OS is trying move files from RAM to hard disk.

Compatibility issues causing not able to run some software. This show the ultimate form of such problems

 

[Alucard]

So what would a person have to do in order to avoid such problems?
I mean I download programs all the time and uninstall them if I don't like them. Does this mean this could occur with me?
If it does, how would I approach fixing it or would it be impossible to fix since you said "it cannot be undone"?