dude check out following links one of solution might help or
try W32.Downadup.B removal tool.
How to remove W32.Downadup.B : Virus Solution and Removal
How to remove W32.Downadup.B worm | remove-malware.net
Download W32.Downadup Removal Tool 1.0.3 - Freeware removal tool that will scan and...