I have the same thing happen on two different servers.
Both are Windows Server 2012, added to domain. Once the DHCP role is added, the server is authorized. Eventually the Task Manager comes back and says there is a post install configuration needed for the DHCP role. Try to do it as a domain admin, and get the dreaded "failed to open registry key on target computer to set the status of post configuration task"
What is the solution to this? Kind of irritating!!!!
Minoo Jalal