uh .. not the app data folder, you should delete the Limewire folder inside it.
http://www.gnutellaforums.com/genera...der-vista.html
Do steps 5 & 6 here:
Fixes for Limewire (click on blue link)
If that does not fix it, then reinstall both Java & LW, cleaning system before reinstalling, rebooting after installing Java.
http://www.gnutellaforums.com/333278-post2.html
BTW instead of that version LW, try the Beta:
LimeWire 5.2.4 (Beta) - Lime Wire