Those files:

!!!(something).zip
(Your Exact Search Query).asf

Etc.

They are gnutella viruses. When executed, they reside on your PC and use you gnutella client software to respond to incoming search queries (from other users). The virus creates the file with the appropriate name contain a copy of itself and maybe some "padding" to vary the size and will have a name ressembling the file you are searching for.

Check www.antivirus.com and search for "gnutella" or ".zip" or ".asf" and read the results.