Check the 1st section here WARNING: Viruses on network you should be aware of! (click on link) & you'll find a number of online virus checks you can do.

You never did tell me. Who is your ISP (internet service provider)?
Lack of search results generally points to an ISP using a p2p shaper.

I don't know how keen you are about this thought, but you could try installing another gnutella program to see if you have the same problem. Try BearShare Lite http://www.filehippo.com/download_bearshare_lite/