DC Troubles, Issues, Demoting etc

[steelrazor]

Has anyone Demoted a DC on a live network?

I've got a bit of a problem. A while back one of my colleagues accidentally named a pc in the library to "Library" which shared the name of the Library Server, also being used as a secondary DC. After this happened, we've not been able to connect to it over the network at all. It's also not functioning as a Domain Controller even though in it thinks it is. So, if I type in "\\library\" we get a "Logon Failure: The target account name is incorrect" message.

Obviously this is buggering up replication on the network, among other things. Plus, all the links to any library server applications and shares can't be accessed (although i've kinda sorted that by moving across stuff to our main DC (Curric05).

If I do a DC Diag on Curric05 I get numerous replication errors plus... (not sure if this is anything) but on the service test it says "TrkWks Service is Stopped" and "TrkSvr Service is stopped".

Now, this problem with the library server wasn't really causing many problems until yesterday when in one IT room (and it seems to be just one at the moment) it started to not pick up Group Policy.
After checking up on Event Viewer i got the following message under application events:
"Windows cannot obtain the domain controller name for your computer network. (The network path was not found). Group Policy processing aborted."

It's a bit of a strong guess but i'm guessing this is about the pc's trying to connect to the library DC to get group policy?

If it is I guess I need to demote the Library DC. Has anyone done this in a live environment at all? Any suggestions?

Or... am I totally wrong about this being the reason group policy has decided to not work??

Any help would be appreciated!

(all this happens when my boss is on holiday! great!)

[Geoff]

You need to seize the FSMO roles off the library server (if it has any).

http://support.microsoft.com/kb/255504

Then do an authoritative restore of AD back to the library server.

http://support.microsoft.com/kb/241594

[djm968]

You probably wont be able to demote the server, I would manually delete the server from active directory using a metadata clean-up

This step by step guide gives you the exact steps you need to follow.

[djm968]

Sorry forgot to paste the link!

http://www.petri.co.il/delete_failed_dcs_from_ad.htm