DHCP DNS AD all died at the same time!
So this weekend it seems that my PDC decided it didnt like something and flaked out. (Out of interest a restart made it all better)
I have a huge amount of errors so I will pick the few that I feel are most relevent -
NTDS (504) NTDSA: A request to write to the file "C:\WINDOWS\NTDS\edb.chk" at offset 0 (0x0000000000000000) for 4096 (0x00001000) bytes succeeded, but took an abnormally long time (116 seconds) to be serviced by the OS. This problem is likely due to faulty hardware. Please contact your hardware vendor for further assistance diagnosing the problem.
NTDS (504) NTDSA: The logfile sequence in "C:\WINDOWS\NTDS\" has been halted due to a fatal error. No further updates are possible for the databases that use this logfile sequence. Please correct the problem and restart or restore from backup.
The Knowledge Consistency Checker (KCC) encountered an unexpected error while performing an Active Directory operation.
Object distinguished name:
Active Directory was unable to establish a connection with the global catalog.
The Security Account Manager failed a KDC request in an unexpected way.
etc etc etc etc LOL!
The DHCP service failed to see a directory server for authorization.
So, where the hell do I start to look for a cause?