Re: PDC crashed

-Can you recover that DC?
-If the clients can't login , then you may have different problems depending of your network configuration. Do you have alternative DNS servers on your network? Are clients configured with additional INTERNAL and VALID DNS servers? Are you in a multidomain environment? Is that available DC a GC? What error are you getting from client side?

I hope that the information above helps you.
Have a Nice day.

Jorge Silva
MCSE, MVP Directory Services