Are there all green or blue connection quality bars at the bottom left of the LW screen? If not then you might be firewalled. See
http://www.limewire.com/english/content/firewalls.shtml
Make sure your Java is up to date (try re-installing it) & perhaps even delete your LW preferences folder whilst LW is closed. See Fixes for Limewire:
http://www.gnutellaforums.com/showth...threadid=36420 Fixes for Limewire
You should wait 10-20 after opening LW before using.