Are you using Pirate Edition? If so, are you using File_Girl71's version: http://www.gnutellaforums.com/359817-post3.html or the original as posted by metapirate: http://www.gnutellaforums.com/359709-post1.html

I think a few people have had probs with AVG not working properly in the original version. File_Girl's version does not include AVG.

If you already have a good AV installed, keep it updated & use that to scan files after download & before opening the file.