When I search for a song, it says at the top of the result page that if it doesn't have a lock sign in the quality section that it could be a virus..but none of the search results have a lock sign, they all have 4 stars, so does that mean that they are all viruses?

The lock sign only applies to Limewire updates. If you see an update in the search results without a lock sign, it is fake. Most viruses on the network are probably found in fake program files. With audio and video, there may be a few viruses (not sure...I've never seen one), but mostly you'll be frustrated with fake files.

Hope this helps

Dan