Downloader - Filename & Location "Unavailable"

This blasted thing keeps coming back, in spite of following the removal instructions to the letter.  Problem is, I can't find it in the registry or in the filesystem because when it's detected it doesn't tell me where to find them - filename and location are "Unavailable".  So how did it detect the thing?  Better yet, how do I zap it fer once & fer all???  Any help greatly appreciated!

 

XP sp3, Symantec Anti Virus v10.1.4.4000 (2006)