Sounds like you have a virus. There's info about it here
http://www.gnutellaforums.com/showth...threadid=39612
and
http://www.gnutellaforums.com/showth...threadid=41432
The second thread has good advice & also a link to norbiesworld... if you can't get rid of the virus then he'll be able to help you.
Make sure you have a good, up to date AV program & scan files before you open them