It's probably the klez/elkern virus (worm actually). Have dealt with it many times before. goto www.symantec.com and download the fix from their site. It's a good fix and it works.
Bootup into safe mode and make sure that all restore features are disabled and then run it. also make sure any anti-virus apps are disabled...!!

http://housecall.antivirus.com >>> it's an awsome online scanner but very often if your machine is infected you wont be able to get to this page....!!