Since yesterday a problem with Windows 8.1 and my Zentyal Server v4.1 occurs, the problem is that despite entering data and password does not recognize them and stored them in either Windows credentials.
The problem is a storage option and cryptography that Samba 4 is not yet implemented.
To fix just have to uninstall updates KB3000850 - KB2992611 - KB3038562 and then disable them so they do not reinstalled.
The bug with Samba 4 will be resolved shortly I think, but now I leave this post in case anyone has more trouble do not waste your time trying solutions that will not work.
More information in:
https://lists.samba.org/archive/samba/2015-January/188458.html
https://social.technet.microsoft.com/Forums/windows/en-US/47faab6b-d717-4068-bee4-c694811e0066/credential-manager-problems-error-0x80090345?forum=w8itpronetworking
Greetings!