AD integration lost! Error message: Unable to access domain controller

I need help desperately (where are you Schoun Regan and Michael Bartosh?).

I am one of four techs at a local school. We had initially set up and successfully bound OS X Server to AD (using single sign on). This has worked flawlessly for 8 – 14 months.

As far as I know there have been no updates recently made to our OS 10.3.9 server, but we recently swapped out some older 3Com switches to managed HP blade switches.

Now, here is the thing. I am getting an error message from the Directory Access control panel that says: “Unable to access domain controller.” and “”This computer is unable to access the domain controller for an unknown reason”.

Now the crazy thing is all the settings look right. The dns, the reverse lookup, the kerberos, the tickets. There might be one thing we are missing, but I don’t know what to do.

The crazy thing is I tried to unbind AD through Directory access (to rebind AD) and I get that blasted message!!! The settings as we had it seem to be bound, but I cannot unbind this thing to try and fix it.

I even temporarily placed a patch cable from the xserve to a wall drop rather than the switch. Same deal.