Have you run an AV scan recently? I can't really find any other solutions apart from what I gave you before. If all these tools aren't working, maybe you have a virus? Been downloading any program files recently?

Someone else might come along & have more ideas. But for now, I'd do an AV scan & maybe spyware & adware scans, too. Here's a thread about virus probs:
http://www.gnutellaforums.com/showth...threadid=41432

See how you go with this, sorry I don't have more answers