I'm not sure whether that particular surfboard modem requires the forwarding of port 6346 or not. Some of their other models do require this. I'm sure it will say in your modem manual how to foreward a port if it has this capacity. Else you can ask your isp for instructions.

For now you can do this: Force IP instructions & sample image & ensure your firewalls are set correctly whether they're in use or not: http://www.limewire.com/english/content/firewalls.shtml

Dare I ask but who is your isp? Some isp's do limit p2p or worse.

There's another 2 things you can try: Update Java: Java 1.4.2 (click on link)

Delete your LW prefs called .limewire found here: C:/Documents And Settings/your_username/.limewire