I've been trying to fix an old P4 machine, which to begin with was filled with viruses/malware.
I went through this process:
1) Ran TFC in safe mode under admin account
2) Ran ATF cleaner in safe mode under admin account
3) Ran MalwareBytes and Spybot SD
4) Ran Avira found 4 infections on 1st scan but froze
5) Ran again and only found 2 infections and was able to delete and copy and to quarantine
6) Ran combofix and removed malware
7) Ran combofix with update and repaired infected system file
8) Ran TDSKiller to remove google redirect virus
Now the issue seems a lot better, the computer is usable, still very slow, but the problem is that it still randomly freezes. It froze during windows updates, during scans and also when idle. I re-ran all scans in normal mode for a final cleanup, ran a registry cleaner and all temp file cleaners again under the user account (local admin rights).
Also another issue is that certain items in the start menu are missing, for example in accessories, systems tools, it shows empty.
I don't know if this is a hardware issue or not, because sometimes the PC will work for a few hours and freeze, other times in a matter of minutes. The screen stays on and frozen, Cant move mouse or use keyboard at all, no num lock or caps lock light.
Any idea what could be wrong? If you need further info, please let me know. Thanks in advance.