Already done that......
I've got Ad Aware and Zone anti-virus too, both up to date. Prior to turning off my PC I always delete files, history, do the clean-up, run the Ad Aware.....nothing helps? The last time I had something similiar to this with a different brand PC was when I phoned the factory tech @ $3 per minute. After one hour of worthless "advice" nothing changed! I don't know....are these PC's programmed to fail at a certain time in their life spans so that people like me will go buy a new one? Maybe that's a possibility.