If you have a Windows PC that you think may have file corruption, one easy check is to run the system file checker command below. This scans the system for corrupt files and tries to repair them automatically. In some instances you may need to install the original install disk, it will prompt you if necessary.
sfc /scannow (repair)
sfc /verifyonly (scan only)
System instability could also result from virus, malware, or similar. Most already are aware of these issues and what can help prevent them. A repair can be much more difficult and time-consuming. One of the best methods I have found is to pull the HDD out, plug it into an HDD to USB adapter run a scan from a separate computer. None of the files are loaded into memory, you have full control, etc.. This can save hours of trying to run safe mode, manually trying to work around the files loading while trying to isolate and remove them. Just plug it in, run it and walk away. The problem is you need the adapter. It is a good cheap investment if you dig into computers at all.
In some instances what may appear to be a corruption or virus could be the result of a dying HDD. Run a disk scan and check the results. The results will be in the Event Viewer log. If it finds and repairs issues, good, but be sure to start looking for a new HDD.