Try enabling UPnP within the router & choose that option from LW's tools > options > advanced > firewall config. Apply > ok to save the change.

If that doesn't fix things (give it a few minutes to see if the wall disappears), try forwarding a port through the router. Click on the link below & you'll find instructions. Don't forget to set up a static IP address first, you'll find instructions for that within the link below as well.
http://www.portforward.com/english/r...i/Limewire.htm

*You're better off configuring the Windows firewall, rather than running without one
Firewall setup