/nod to Astrokitten... I forgot to mention the potential for an existing viral infection causing his issues.
Doh! (/smack Gandar)
Here is the link to
Trend Micro Online Virus Scanner
I hope it helps. I've had occasion to use that one myself. Ick.
Alternately, though, you can try booting to your NAV CD - should be able to run a cmdline virus scan from there, too. Especially if you made the Norton Rescue Disks at your initial install.
Good Luck and Keep us posted...
~Gandar
p.s. VIRUSES SUCK and SO DO SCRIPT KIDDIES THAT MAKE THEM.