"No authority could be contacted for authentication."

I have been giving weekly webinars using a demo environment that mimics 3 SharePoint farms (2 x MOSS 2007, 1 x SPS 2003). While prepping for tomorrow's demo I ran into some very strange SharePoint behaviour.

For no apparent reason, the default site collections no longer worked - they failed to load and couldn't see each other via a web browser. However, on both 2007 farms, I could still see and use the remote internet site collections just fine (using anonymous authentication on port 8000).

In the Event Viewer, various errors started complaining about DCOM saying things like

Reason: The trust relationship between this workstation and the primary domain failed. (Exception from HRESULT: 0x800706FD)

And when I viewed the other sites in the browser, I would get "Service Unavailable" errors and, eventually:

No authority could be contacted for authentication.

These errors, plus the fact that I could still use anonymous authentication, obviously pointed to something beyond SharePoint being the culprit. When these kind of authentication errors abound you don't have to look far beyond Active Directory to find the guilty puppy.

I eventually ran across this very helpful post by Noman Juzar Lakdawala on the ASP.NET forums:  http://forums.asp.net/t/986545.aspx

I followed his instructions and removed my servers one at a time from the domain, deleted the entry in the Domain Controller, and then readded them. Everything works now!

Not sure why AD got corrupted in the first place, so I will continue testing, but so far so good.  Thanks Noman!