Something may have gotten corrupted.
Uninstall java. With LW shut down go to the add/remove programs control panel and uninstall your current version of java. Now download and install
J2SE Runtime Environment (JRE) 5.0 Update 11(use the offline installer):
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11
Then uninstall LW. Don't use the add/remove programs to uninstall. Go to the program folder, it should be found at C:\Program Files\LimeWire\Uninstall.exe. Double click the Uninstall.exe file. That should uninstall it. Then search your hdd for limewire and delete any references. Now dl and install LW using the offline installer:
Lime Wire » Download LimeWire