I read this with much interest, as I recently went through a series of hoop-jumping exercises to get my home box to run right. In my case it was a "worm" that had been picked up (probably by my 14 year old's instant messaging) and was keeping some of the .exe files from running. I couldn't even run the virus program properly to fix it. Eventually, the tech folks at Norton pointed out that you could get a diagnostic program to run from their site, which would find the bad files and isolate them. That, about 20 pages of instructions, and a one year extension of my anti-virus software license got me back on track.
Lesson learned? That annoying, time-consuming virus detection software is worth keeping around and active.