Its the sobig worm...download and run this tool:
http://vil.nai.com/vil/stinger/
Then do this:
go to http://www.lurkhere.com/~nicefiles/ , and download 'Hijack This!'.....
Unzip it to its own folder, doubleclick HijackThis.exe, and hit "Scan".
When the scan is finished, the "Scan" button will change into a "Save Log" button.
Press that, save the log somewhere, and please copy & paste its contents to the forum.
It will possibly show other issues deserving our attention, but most of what it lists will be harmless or even required, so do NOT fix anything yet.
Someone here will be happy to help you analyze the results.
If you have anything disabled by MSConfig or any other startup manager, please re-enable it before scanning to post.

http://vil.nai.com/vil/stinger/
Then do this:
go to http://www.lurkhere.com/~nicefiles/ , and download 'Hijack This!'.....
Unzip it to its own folder, doubleclick HijackThis.exe, and hit "Scan".
When the scan is finished, the "Scan" button will change into a "Save Log" button.
Press that, save the log somewhere, and please copy & paste its contents to the forum.
It will possibly show other issues deserving our attention, but most of what it lists will be harmless or even required, so do NOT fix anything yet.
Someone here will be happy to help you analyze the results.
If you have anything disabled by MSConfig or any other startup manager, please re-enable it before scanning to post.