It's generally either an incomplete Java installation when it's installed over the net, or likewise for LW, or the Java version doesn't work well on your particular system. If you have Java 1.5 then uninstall it using the Add/Remove control panel & instead install Java 1.4.2 using the offline installer. Or if you have Java 1.4.2 then install Java 1.5.
Fixes for Limewire
See these posts also for pointers:
http://www.gnutellaforums.com/showth...threadid=39684 change to win 2k compatibility OR
http://www.gnutellaforums.com/showth...threadid=39536
OR
Fix for opening Limewire "Fatal Error Message"
Did you configure your firewall so it allows LW full access (advisable not to have 2 active firewalls b/c they can interfere with each other);
Firewall configuration instructions (click on link)