Have you made sure that the windows firewall is off?

Your router has an internal firewall. Try port forwarding, here are the instructions for your router.
http://www.portforward.com/english/r...G/Limewire.htm

Don't forget the step of setting up a static IP address first. The port forwarded through a router, LW's listening port & port in the 'manual port forward' box all have to be the same number

If that doesn't help, try reconfiguring the Norton firewall.
Reconfiguring Norton Firewall