[Samba] Fix for Windows 8.1 RSAT error when creating users

[Daniel Menes]

I created a new Samba4 AD DC, and attempted to add users and groups from 
a Windows 8.1 computer using the Remote Server Administration Tools. 
While I was able to create groups just fine, attempting to create a user 
failed with the message "An Error Occurred. Contact your System 
Administrator."

A quick Google shows that others on this list have had this and similar 
problems, but I was unable to find a satisfactory solution here. I 
thought you might be interested in what worked for me.

According to Microsoft, there is a known issue with a Windows Update 
which may appear as KB3000850 or KB2992611. Others have suggested 
removing this update, which may or may not be practical. However if you 
look at http://support.microsoft.com/en-us/kb/3000850 in the "Known 
issues in this update" gives a registry hack fix.

In regedit, under the key " 
HKEY_LOCAL_MACHINE\Software\Microsoft\Cryptography\Protect\Providers\df9d8cd0-1501-11d1-8c7a-00c04fc297eb", 
create a DWORD entry with name "ProtectionPolicy" and value "1".

After a reboot, this fixed the problem for me.

--Dan Menes