First try to delete your ".limewire" preference folder, when LW is completely closed (i.e also in the system tray).
If that doesn't fix it:
Uninstall LW and all your Java, download the JRE offline installer from Java here:
http://java.sun.com/j2se/1.5.0/download.jsp
Install the Java with the offline installer and reinstall LW. That should fix it.
