you don't have wins servers in your dmz don't you
There is some activity with irresponsible released exploits against WINS. As a precaution till Microsoft gets a chance to release a patch for it, we can only reiterate the urgent and continued need to make sure you block the unneeded ports in your firewalls (either the XP2 or the corporate firewall). Ports 42, 137-139, 445 both TCP and UDP can be safely blocked for most applications. source : internet storm center
There is no reason why you would have WINS servers in your dmz or on the internet and if you have, you probably don't need them there. And your WINS servers don't need that kind of connectivity to the internet either. Those ports should have been closed since Sasser on your firewall, whatever if it is a personal pc or a network.