You should configure your mcafee firewall to allow LW access:
http://www.limewire.com/english/content/firewalls.shtml
Are you happy with LW 4.3.3? The most recent version is 4.8.1 which has better firewall support:
http://www.limewire.com/english/content/download.shtml
Try deleting your LW preferences folder whiilst LW is closed; instructions here:
Fixes for Limewire
Do this simple test for us. Using your browser go here:
http://www3.limewire.com:6346/ The page should say ‘Test Page was a Success’. What happens when you go there?