Welcome to the forum, Cathode_Ray.

Prevx identifies a downloader using the file name stup9x.exe as Drev A (2nd from the bottom of the list)

http://virusinfo.prevx.com/pxresearchfiles.asp

Try scanning with the free version of Prevx, which you can download here, to see of it solves the problem

http://info.prevx.com/downloadremove.asp