You need to disable the "messenger service". Our friends at mickeysoft nere nice enough to enable this "deamon" by default along with a host of other useless gunk(services). This is not related to MSN or "Windows Messenger" but more like the unix "talk". I think they got one their "windoze uptadez" patches to close this hole after all their poor suffering customers started getting hit by all that tasty popping spam and screamed to high heaven.
It's trivial to get rid of, just google for disable "messenger serice" or some such. You will get mucho hits. goodday, __ sodjiin
