Ten reinfections in 2 days by W32Silly.FDC

I've been trying to clear a virus and trojans from my PC in the last couple of days, but they keep popping up again.

Norton. The security history reports that W32Silly.FDC has been quarantined about 10 times.  Twice, Norton reports quarantining Trojan.gen.

 

Some other symptoms -- IE was set to use a proxy -- but I have no proxy.  I cannot disable System Restore -- the checkbox is disabled by group policy.

 

If I log onto the computer with my husband's account, there is no access to the Internet.

 

I've backed up my files to a removeable drive, so I can reformat the drive and start over if I have to, but I'm afraid my backups might be infected, too.  What a mess!

 

I've run full scans with Norton, MalWarebyte's Anti-malware, and have run the Norton Power Eraser.  Each time a threat is found and cleared, but they keep coming back.

 

What do I do next?

 

I'm on XP Pro SP3