Got a call from a client today complaining that he could no longer access the Internet. He's running Zone Alarm 7.
Trek out to the site and lo and behold, we can ping IP addresses thru the firewall, but we can't resolve any names. Turns out DNS had a big hole in it, and it's been patched by the major vendors, Microsoft among them.
So, Microsoft rolls out KB951748 yesterday as part of Patch Tuesday, and this morning all the machines set to autoupdate who are also running Zone Alarm find themselves out of luck.
The quick fix is to run ZoneAlarm's Internet Zone Security in "Medium" mode.
Zone Alarm released a knowledge base article suggesting three options: the aforementioned "medium mode" fix; uninstalling the patch or adding your DNS servers to the trusted zone.
Adding the DNS servers to the trusted zone is the most secure solution as it allows you to run in full stealth and still enjoy the "benefits" of the Microsoft path.