Did you try all of the fixes in the help thread, & did you have trouble with any of them? After you deleted the preferences folder - did you have to go through LW's setup wizard all over again?

Did you try updating your Java (just that you're still using an older version)??

If you did try all of those fixes, you could look at port forwarding. The instructions are here: Port Forwarding for the Linksys WRT54G

You'll need to set up a static IP address first, there's a link to instructions within that port forwarding link. LW's listening port, port in the 'manual port forward' box & port forwarded within the router's setup should all be the same number. Try a port like 65000.