Trouble with Active Directory

I have a domain with two domain controllers (DC1 and DC2)
I can access resources in DC2 from DC1 but not from DC2 to DC1, there are also troubles in replicating AD from DC2 to DC1, I mean I create a new user in DC2 and it is not replicated to DC1 for example.
I have event ID 1000 “Windows cannot access the registry information at ….” every 5 minutes in DC2.
Can anybody help me, please?

Thanks a lot