2012 R2 DC crashes after import Root CA from 2008 R2 DC/CA (with same name)

Hello Everyone.

We migrate a Windows Server 2008 R2 DC with Root CA to an Windows Server 2012 R2 DC with same IP and Computername on a new VM. The Windows Server 2012 R2 works fine before we import the Root CA Information from a Backup (http://technet.microsoft.com/en-us/library/ee126140(v=ws.10).aspx)

After import the Root CA Information, we can´t rename any object, OU, user account, etc, whichever DC AD Users and Computers is pointing at, lsass.exe will crash and the DC will reboot after 60 seconds. Remove ADCS is no helping.

Depromote DC and removing ADDS, reboot... and promote the W12R2 to DC is the same Problem. Now we delete (properly) the Server and reinstall the W12R2 OS and promote the Server to DC. After new install the rename any object works fine.

Regards Achim