just a thought. I've seen what that virus can do to a computers drive. Have you scanned the files for that virus??
I have added an external 240g HD to my system (XP sp2), I have a broadband connection. On checking the drive properties recently, I noticed that this drive was showing almost full although the total of all the files added to around 60g! I removed all files, formatted the drive & replaced the files. I monitored the drive and straight away it registered less and less available space. If I close my internet connection the used / available space does not change. I have a BT broadband router running a wireless network, Norton antivirus, and all my emails are checked in Mailwasher before downloading.