Certificates Question

My DC's are squaking about failing to renew their certificates. It's stating that the RPC server is unavailable with Event ID's 13 and 16. I am not sure where the certificates are supposed to come from. I have never installed Certificate Services on any of my DC's or any other server I have running. Should this be the first DC we created in our network? It was an NT PDC that had an in place upgrade done on it. It has recently died and needed to be replaced. Its death forced us to seize the FSMO roles due to it not transferring them to another DC before it kicked the bucket. I am running Windows Server 2003 SP2 on all of my DC's (two Root DC's and two Child DC's) and all are configured as GC's and DNS. Do I need to install a CA in my domain for this to work? Everything is working at the moment but I need to settle this down.

Any Reply would be greatly appreciated -