Hello, I am facing a strange situation: I have downloaded the sources with git, configure and compiled (Samba Version 4.1.0pre1-GIT-76fa5ee) just like in the HowTo doc, here: https://wiki.samba.org/index.php/Samba4/HOWTO All the tests were ok. I am using internal DNS of Samba4. I have successfully added one XP machine to the domain controlled by samba server. On this XP system I have successfully installed Windows Server 2003 Administration Tools Pack and I am able to "see" the active directory structure in the management consoles. I have added the scripts to autostart samba after rebooting (using upstart services in ubuntu). Now, after I am restarting the server machine, samba4 starts ok, but when I try to access the active directory structure I am getting a message informing that the Naming information cannot be located because: The Local Security Authority cannot be contacted. In the Event Log of XP client system I have two warning messages issued by LSASRV.DLL: 1) The Security System detected an attempted downgrade attack for server ldap/samdom.local. The failure code from authentication protocol Kerberos was "There are currently no logon servers available to service the logon request and the second, 2)The Security System could not establish a secured connection with the server ldap/samdom.local. No authentication protocol was available. In log.samba file I have: [2012/11/13 11:32:58, 2] ../source4/auth/ntlm/auth.c:420(auth_check_password_recv) auth_check_password_recv: NO_METHOD authentication for user [(null)\(null)] FAILED with error NT_STATUS_NO_SUCH_USER If I restart Samba4 service, I can access the active directory structure from the XP client system.