My daughter was using my computer... AVG scans every night at 3AM so I have rarely had a virus problem. She said "Dad the computer says you have 351 viruses". I knew immediately it was something she got into. The nice virus offered me a chance to purchase an anti virus program for $59.00 lol

I ran AVG and it was 1 virus (3 files), AVG removed the virus, however the system was very unstable after that incident, had to eventually reload windows.

One thing you should do is Backup, Backup, Backup.... Since that incident I have bought a nice large USB Hard Drive that I save all my important files to.