[IIS 5.0] Windows Integrated Authentication Problem

So yesterday we had some fun trying to online a new domain controller on our network. It didn't quite work out the way we wanted it too (I wasn't involved, so do ask why... :D). After demoting the new DC, and taking it offline, we started noticing problems with our IIS 5 websites that use Windows Integrated Authentication.

Opening a site that was set to basic/windows integrated authentication (with no anonymous access enabled) would previously open without any prompt for user name/password. Now we are receiving prompts for passwords/user names. This was not isolated to a single site, but is evident across several sites / web servers.

Besides a simple reboot (the obvious windows fix-it-all) is there anything worth trying to resolve this?

Also, I just discovered that when added to the trusted sites list in IE, the authentication works like a champ (no password prompt). However, these sites should be recognized as Intranet Zone websites. It appears that they are not for some reason. Does anybody know how IE determines if a website is in the Intranet Zone?