Go to Add/Remove control panel & select Java & use the repair option. See if this fixes it. If not, uninstall Java & downld it again (but save it to your computer, don't install over the net!), then install it. If you have Java 1.5 & it's not working then uninstall it & try Java 1.4.2; you can get a link for this here:
Fixes for Limewire