Sounds like malware to me.

Grif notes tools to scan with at http://forums.cnet.com/7726-6132_102-5098912.html?tag=posts;msg5099421

Notice Grif's advice on how to get those tools onto the machine.

Because of those new nasties out there, I strongly advise folk to keep backup copies (MORE THAN ONE!) of stuff they can't lose. It's not a matter of if but when.
Bob