When you changed over to Pro, was it just an upgrade (ie the same version number that you'd been using when you had basic) or did you update to a newer version of LW as well?

It's a good idea to delete LW's preferences folder after up*******upgrading...give that a try, it won't hurt anything. You'll just have to go back through LW's options & reset things afterwards. See point 3 below for instructions. If you've used much older versions of LW in the past, you could have a folder in point 2's location as well...so check in both places.
Fixes for LimeWire

Double check your XP firewall config, just to make sure nothing's changed.
Firewall setup

Your router has an internal firewall. If the router supports UPnP, make sure it's enabled & then use the UPnP option within LW's tools > options > advanced > firewall config. Apply > ok. Give it 15 mins & then see if the brick wall is gone.

If that doesn't do the trick, it's time to port forward. Use the instructions here
http://www.portforward.com/english/r...4/Limewire.htm

Don't forget to set up a static IP address first...otherwise port forwarding won't work
Also, the port number forwarded, number of LW's listening port & the number in the 'manual port forward' box all must be the same.

Sometimes changing to a new version can give you firewall probelms where there weren't any before