I recently had peculiar set of  events leave me with a single AD Server placing  it into a UNC Rollback state.  I replaced the server with a back-up image, tried restoring the System State in DSRM, no luck. Every avenue I tried left the system in the same state upon reboot. After hours and many failed attempts this was the last remedy for me…

Restored the Image of the Server (to put the system back to square one) then restored the system state in DSRM, this did NOT work (still in UNC) , opened REGEDIT and deleted the key

“Dsa Not Writable” under “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NTDS\Parameters

Upon reboot the Active Directory services started and netlogon and the balance came up as expected. Obviously reg edits are at your own peril. I couldn’t find any work around solutions on the web other than rebuilding Active Directory from scratch and that really isn’t a solution at all in my book. So if your faced with a similar problem give this a shot, let me know if it helps you too.

The environment is operating in mixed mode and this was on a Win2K server SP4.