Two possible scenarios.....
A corruption of the LW preference folder...
Read here on how to delete this folder (Point #2 & 3 in Fixes for Limewire)
http://www.gnutellaforums.com/showth...threadid=36420
Second, your ISP has started to throttle the bandwidth usage (especially for P2P programs). Try and download a magnet file from here and see what speed you get for it, then post the result as well:
http://www.magnetmix.com/video.shtml