There are a few different fixes to try here:
If LW 4 Will Not Connect
If you're using 2 software firewalls at once, they can conflict with each other & neither one will work properly. Try disabling XP's firewall & then reconfigure the Symantec firewall to allow LW - remove all LW rules & then add them again from scratch.
If that doesn't help, delete LW's preferences folder next. See the top link for more info

Otherwise, try the other fixes (deleting/replacing gnutella.net might be the next thing to try).