Crashes, lockups, and problems downloading

I'm running Windows XP pro, and have been having these problems since about a week or 2 after doing a fresh install.

Many games that I play (especially online ones) tend to crash more often than one would expect them to. I use Ventrilo for voice communication, and it will totally lock up (not crash, just freeze so that I can't hear anyone and they can't hear me) anywhere from 1-5 times per night.

To top it all off, the only time I can download files from websites is immediately after a reboot. Doesn't matter if I use Firefox or Explorer. If I try downloading something after the computer has been on for a while and running other applications, I get a corrupted file every time.

I'm fairly sure it's either a virus/spyware or a bad stick of RAM. I've run SpyBot and AdAware, and done a virus sweep with AVG. None of these helped. Any other suggestions before I go buying more RAM?

 

I see you've taken some steps to remove malware, but were they done in safe mode? What about the malicious software removal tool?

I would recommend that you run through the malware removal thread. That'll get any nasties on your system.

Also, I would update drivers. After a fresh install, you probably have older versions.