Hyper-V could not initialize (rights?)

Hello,

I have an WIN2012 R2 Server.
Unfortunatley it is serving as a DC (I know this is not recommended).

I set up the HYPER-V role and when I start I receive with a newly created VM (no etwork connected yet):

'TEST111' could not initialize. (Virtual machine ID 49608249-F381-43E8-BCCF-F6C61CDE68A0)
Event ID 3040

Most likely it has something to do with the rights. I tried to apply this thread, but no luck:

http://social.technet.microsoft.com/Forums/windowsserver/en-US/ae8a90a2-4251-4fbd-b644-72dcd4b5f08c/error-an-attempt-to-initialize-vm-saved-state-failed-when-starting-any-vm?forum=winserverhyperv

I reinstalled the role and it still does not work. It looks like the old Settings of the hyper-v program stay on the machine after deinstalling the role, because after the reboots and Setting it up again it Shows the old Settings.

The process Monitor Shows:

HKCR\Applications\vmconnect.exe : NAME NOT FOUND Desired Access: Read.

Q:

Is there a way to completly clean the hyper-v stuff?

It might be that hyper-v only accepts local admin users (especially on a DC)?