Windows Server 2012 Essentials shuts itself down after some days

Hi,
I have a "Windows Server 2012 Essentials x64 english" installation
and as we already have a SAMBA 3.6 PDC in our company,
I removed all the AD stuff and just joined the Win2012 server
as a member to the Samba Domain because the Windows Server
just needs to run a MS-SQL and Sybase database server.
That worked completely fine within the 180 days of evaluation period,
but as soon I activated a purchased license it started shutting down itself
after some days with the following entry in the eventlog

"The Root Domain Check detected a condition in your environment that is out of compliance
with the licensing policy. This server will be automatically shut down if the issue is not corrected in 5 day(s) 4
hour(s) 30 minute(s). Please look for additional events for Root
Domain Check to troubleshoot."

Of course it can't check the root domain because of the SAMBA PDC, but please,
shutting down the whole machine is unacceptable.
This causes serious damage in the company because people can't work then.
Is there a hotfix or registry change to disable this stupid behaviour?