I'm not sure if you can have Norton running. It's not a firewall issue, so you can't just include Limewire on the list of exceptions. Can you turn off the 'worm' protection and still have some antivirus protection? That may be what you have to do. If you can't figure out how to make Norton compatible with LW, you could download AVG antivirus (it's free). It works well with LW and provides good protection.

AVG Free Advisor: Free anti-virus, anti-spyware and anti-malware tools

Good Luck

Dan