Gnutella Forums - Invalid external address?

Hello, I've had some problems connecting to Limewire for quite some time now and wanted to get it back up and running. Since 4 hasn't worked it in a long time for me, I tried out version 5. Unfortunately, no luck, and I think I've screwed it up even more while tinkering around with it to make it work. It could support firewall transfers before and now it can't because of an "invalid external address". I'm completely stuck and I've searched the forums for this problem but haven't found exactly the problem I have yet. Any help would be appreciated, thanks!

-Microsoft Windows XP Home
-Windows Firewall
-1024 MB RAM
-24.6 GB remaining
-Cable/DSL internet connection
-Linksys WRT54Gv8
-Connecting from apartment complex
-Limewire v5.1.2
-Java 1.6.0_11
-ISP: ICS Technologies, Inc.
-My test worked at http://www3.limewire.com:6346/
-Not necessarily, I also use uTorrent which also has problems running but I don't use both programs at the same time.
-New problem with experienced user, although I have made this connection work in this apartment complex a couple times
-I'm behind a firewall
-I'm using port forwarding since UPnP straight-up does not work (I've tried everything!)
-McAfee VirusScan Enterprise 8.0.0 (some free cheap anti-virus from campus that could be the cause of my problems but it's not like real McAfee anti-virus)
-I live in the USA
-It used to work perfectly at home through my ISP with UPnP and all that stuff. After moving to my apartment complex, it will not on a straight LAN connection from wall to computer (must have a block) but I have made it work a couple times through my Linksys router through Static IP and Port Forwarding, but I must have missed a step or I need to change something again.

Hope I gave enough information, and again, any help is appreciated. Thanks!