Windows XP Domain Problem with another DC

[Jenwol]

Hi

Here is the problem i have
We have dc1 and dc2.
Dc2 is a domain into a domain.
Dc1 just a domain.
I image dc2 (ghost) because we needed that server for 4 days.
Run dcpromo to remove dc2 from the domain
Put dc2 now into a workgroup and reboot.
In dc1 i checked if dc2 was removed and was come up as a computer now
After 4 days we put the images back and now dc1 is complaining that
he is not a domain controller.
How can i solved this problem so dc1 can see dc2 now as it was before.
2: How can i images a dc (backup dc2) so i don't have this problem anymore
3: What to do with replication? or how

Thanks in advance

greets from Jennifer