It's a virus. Info here
http://www.gnutellaforums.com/showth...threadid=39612
and see point 4 here
http://www.gnutellaforums.com/showth...threadid=41432
That second thread has loads of info & advice. It also has a link to norbiesworld. If you go & register at his site (it's free), he will help you get rid of the virus. Always use a good AV program & keep it updated. Scan a file before you open it