Sounds like you've got a virus. There's info here
http://www.gnutellaforums.com/showth...threadid=39612
http://www.gnutellaforums.com/showth...threadid=41432

See point 4 in the second thread, there's good advice & also a link to norbiesworld... he will be able to help you fix this.

Please read that whole thread, it'll tell you what files to avoid in future. You have to take care when downloading. Have a good, up to date AV program & scan a file before you open it.