PG's advice may be somethign to consider, especially with what I am going to say:
the first thing is that a virus on a PC can not affect the hardware (that I am aware of, and since the programmatic issues of the ancient appleII's, not the IIe's). if you are having a fan problem, that is a hardware issue, and decidedly not a virus issue.
I have commented before that I wonder how "normal" people can keep their Wintel boxes virus and malware-free. in fact recent posts by others here tell me that they can't.
If you are running two antivirus programs and they are both disabled, this too can be a hardware issue that is causing corrupted files, though most likely an extreme case of virus/trojan/malware of one kind or another.
last time I cleaned my old-pastor's computer of spyware (malware), he had nearly 5000 entries of files and registry entries that were running and active.
besides your hardware issue that could be power supply or motherboard (main circuit on the computer), you are probably also filled with malware. especially ones that specifically attack anti-virus applications.
I don't know what you have, but my suggestion has always been that if you can afford to buy a computer then you should be able to afford to BUY an anti virus application and the subscription to keep it updated weekly and even daily if necessary.
I have never seen an antivirus (purchased) application like Mcafee or Symantec AV be directly attacked and disabled, I have seen hardware issues cause corruption of their files so that they get disabled, however.
based on your descriptions, it sounds like the malware is the least of your worries (not that, I mean to minimalize that issue), and that you are having system failures as well.
how old is your computer? if it is older than a year (for a "normal computer), then you should have used it enough to justify it's use and another might be the best solution.
If you don't want to go that route just yet, you may need to do what you can to back up your data, and use the system restore that probably came with the computer to restore it to manufacture-initialized state.
probably not what you want to hear. if you have hours and hours of time, you could try to download (on another virus and malware-free computer), a couple anti-spyware applications, like adaware, and spybot; then burn them to CD and try to install them on your infected system, if it will allow it. same thing for AV - if you have purchased an AV program, you will want to try to uninstall it from your infected computer (if possible), and then reinstall from original media/CD's.
good luck.
