eek! wrt54g, they are reknown for problems with their firmware & unreliability. Generally Linksys are very good but the 54 series afaik sucks (excuse the language!)
I've heard of nextnet devices before but know little if anything about them. Almost all wireless devices have internal nat firewalls. The issue is usually to enable UPnP if the device supports it or else, forward a port in order for a port in need to be opened.
Strange it worked before but not now. If the problem is not the device then it may be your isp who may be secretly filtering or blocking p2p programs.
As far as software firewalls go, you should only have one active one. Either choose XP or ZA fw. But you will need to configure whichever one you choose.
Firewall configuration instructions (click on link) & about zonealarm see this extra
http://www.gnutellaforums.com/showth...&threadid=3878
If still problems get back. I'm about to go offline so my answer is a little brief for the time being.
BTW you could also try deleting your LW Preferences folder whilst LW is
closed; instructions here:
Point #2 & 3 in Fixes for Limewire (sample image included at bottom of page.) And see if that makes any difference.