It might be java related. Try uninstalling your current version of java while LW is completely shut down. Go to the add/remove programs control panel and uninstall your current version of java. Then 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
If that fails try deleting your LW Preference folder. Instructions in this thread points 2 & 3(check both locations):
Fixes for Limewire.