1. Try deleting your LW Preferences folder whilst LW is closed; instructions here: Point #2 & 3 in Fixes for Limewire (sample image included.)

If that doesn't work, then check these other options.

Make sure your XP firewall is turned off. This will cause a problem if run alongside Norton FW.

Your model router is known to be unreliable. Linksys are generally very good but I've seen a no. of problems on this & another forum. UPnP is the problem. It doesn't seem to run reliably on that model. I don't know about your firmware version but either update it or else, consider manual port forwarding instead. Instructions are in the very 1st link I gave you in my previous post.