Trying to launch the Recovery Console from the Windows Server disk gave me a bit more trouble than I expected this morning.
The issue I think arises from the initial setup of a server being done with a basic password and then the server is promoted into a domain controller role and gets effectively another password for the Administrator account. The user will use the Administrator password and ‘knows’ that the password is correct, but when entering this password at the Recovery Console login gets an invalid password message and after 3 attempts the computer logs out and restarts.
The issue is that the Directory Service Restore Mode Administrator password is still the original old administrator password from years ago when the server was first installed.
The solution is well documented at the Petri IT Knowledgebase which is where I sourced the correct commands for changing the password.
If you have a server that you cannot boot then this will not help as you need access to the GUI to do this. I have not tried but you may get some success by using a password clearing utility along the lines of my recent experience with my Windows 7 netbook and earlier Windows XP password lockouts.