The first thing you could try would be to delete the LW preference folder as described in Point #2 & 3 in Fixes for Limewire:
http://www.gnutellaforums.com/showth...threadid=36420
Another thing to try would be to uninstall LW and all Java versions on your system. Reboot and then download the JRE offline installer of the newest Java version from here:
http://java.sun.com/j2se/1.5.0/download.jsp
Install it and reboot again, then reinstall LW.