Restoring a Domain Controller problems (USN Rollback)

[readie]

Hi,
We had a disaster over the w/e and had to restore about a dozen servers from backups/replicas. All seemed to go well, except for a DC which had the PDC and RID and the other Op Master role which I can't remember.
It came back (apparently worked for about 24 hours) but now seems to be in a non-replicating state (DSA Not Writeable=4 in HKLM\System\CurrentControlSet\Services\NTDS\Parameters). Microsoft refer to this as 'USN rollback' problems, frequent when restoring from a snapshot or similar image backup . . .
Before I restored the DC I trawled these forums, and the general view was that restoring a DC was not now a problem, only requiring perhaps a few reboots etc. . . . but not in our case.
I restored from backup (not replica). Microsoft suggest that my backup should have included the 'System State' . . does this mean that I should have ticked a particular box on the backup job (which perhaps I didn't)?
Just trying the forum again, in the hope that someone might have come across this, and have some solution or suggestions (the Microsoft suggestions seem, as always, extremely complex).
We don't really want to demote and promote this back to a DC, as it has masses of other tasks like SYNC to Office 365 etc., and ADFS service.
Thanks for any help,
Bob

[readie]

Ah - I have found that my backup job was not 'application aware'. I am now completely lost, or is there a manual process to put things right?

[Gostev]

I believe I recall from my past life that there was a recovery process from USN rollback that included a number of manual steps. Basically, you need to remove the bad DC completely from AD by manually cleaning up references in a few places. Try Googling for the exact process.

[Gostev]

Yep, this was the very first link in Google searching for "recover from usn rollback"
And the process is exactly as I remember it > http://support.microsoft.com/kb/875495
Hope this helps!