virus keeps re-appearing

for about a week now, my norton anti-virus real-time scan keeps finding the virus w32.fbound.gen@mm in the file exchsrvr\imcdata\in\x(where x is a sequence of letters that keep changing). norton was at first able to quarantine the virus and i could then delete it, but from yesterday, it started leaving the virus alone. when i try to find this file, or manually scan the folder, i draw a blank. how can i get rid of the virus? i get about ten of these messages every day.