congrats on getting it fixed!
hey, no matter what you do, a virus can still get in.. it depends on the way it was programmed and how it is supposed to work... just remember to scan your files individually like you say you do all the time. It would help if you had more than one program to do that. Hell, it might not have even been a virus, it could have been some freak incident that rarely happens, but I'm quite certain it was a virus.