Try deleting LW's preference folder with LW completely shut down. Instructions in this thread points 2 & 3(check both locations):
Fixes for Limewire. This will reset all your option settings, so make a note of them first.
If no joy, try uninstalling and deleting all versions of java from your Add or Remove Programs Control Panel. Then d/load and install
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11, use the offline installer.
If that doesn't help, do a virus scan. Let us know how you get on.