Another possibility is that your machine was malicously "cracked" through the use of "Back Orifice" aka "BO."

"BO" permits control of all your machine's functions to be monitored and manipulated from a remote location. It is not a "virus" but it is has potential to be even more powerfully nasty. It exploits a vulnerability within MS Office. It was recently featured (second time/new improved version) at August's "DefCon Convention" in Las Vegas. More information is found at "The Cult of the Dead Cow" (put up "full shields before entering their site!")

There are lots of good Virus Sites - one of my favorites is: Top Ten Virus Reports for the Month. Another good place (subscription is free and they will E-Mail concerning the newest of virus reports) is CERT.ORG Carnagie Mellon's Computer Emergency Responce Team

You truly do have my sympathy, viri are nasty, devasting and a terrible waste of time,money and energy.