Hi Dann and Welcome to the Gnutella Forums.
Not sure how long you've used LW but there are Tons of Viruses, Worms, Fake and Corrupted Files on the Gnutella Network. I would assume this might be what you are experiancing.
These Forums offer more info on this subject than I can begin to tell you. You might use the Search Function to get more valuable info. It is also a good idea to filter a few File Extensions that are known to be hazardous to your computers health. You can find all of this info by doing a few searches. Hope this Helps.