Sounds like you have a virus. These 2 threads have a lot of info
http://www.gnutellaforums.com/showth...threadid=39612
http://www.gnutellaforums.com/showth...threadid=41432

Point 4 in the second thread deals with your problem. It also has a link to norbiesworld... he can help you get rid of the virus.

Be careful what you download. That second thread has a heap of good advice. Always scan a file before you open it