It is probably a red herring, but just check to see if you have any of these files on your system:

svcinit.exe (should be in windows\system\)
web.exe (normally in c:\)
tapicfg.exe (also in c:\)


EDIT: You say that you have scanned for viruses. Did you do that in safe mode? also you should Get AdAware 6 from lavasoft, and Spybot Search & Destroy, update them and run them in safe mode.

It sounds like your video card drivers I must admit, but adware and spyware can create memory leaks. So I think we should eliminate that possibility first?