Wondering Why,
I am having similar problems on my system. I was using a cable modem, and Limewire fine for many years, We just switched to Verizon DSL, and Limewire won't connect and search. I take my laptop to another hot pot, and can connect without a problem, so I know it the DSL.
I changed within Limewire my Manual port forwarding to 59998 in both bozes (manual port and Listen on port).
I changed my ROUTER (as explained on the link) to Port Forwarding, start port = 59998, end port = 59998 with an IP address of 192.168.2.100. (router is 192.169.2.1)
i am using Windows XP, but outside of that, my setup is pretty much the same as the other one listed here.
I followed the link you had posted, but it still didn't seem to work. Do I need to change the settings on my MODEM as well? if so how do I do that?

thanks for any help.
-ron