Try downloading the latest Java client from sun microsystems 1.4 i think they're up to. get it here
http://java.sun.com/j2se/1.4/download.html
I'm running Limewire on a Win2K server, had a similar problem, downloaded the updated version of the Java System files, which work quite differently from Microsoft's Virtual machine, and it solved my problems, as a matter of fact it solved many other problems.
After you d/l it be sure to uninstall the 1.3 client and restart limewire ... it will say that it cant find its client ... direct it to the 1.4 client and you are set.