I'd suggest removing Java using your Add/remove programs control panel. Then re-installing using the "Offline" Java installer: Java 1.5 (take the JRE) which is about a 15 MB download.

Also, delete your LW Preferences folder whilst LW is closed; instructions here: Point #2 & 3 in Fixes for Limewire (sample image included at bottom of page.)

If still problems, try step 5 in the previous link about changing compatibility mode of LW to either windows 2000 or NT.