samba - Feb 2008 - create_builtin_administrators: Failed to create Administrators

Strange problem,

Trying to run a samba server as a PDC, I have created samba users and shares. I
can access the shares however I am unable to connect to the domain. If I switch
my settings on a win xp machine to make him a member of the domain then I am
asked for a username and password. I have created a root samba user and if I
connect like this user I get the following error:

The following error occured attempting to join the domain"domainxx"
The username could not be found.


Also in the /var/log/samba log files I get the following messages for every time
I do a login try like this:
[2008/02/21 09:29:45, 0] auth/auth_util.c:create_builtin_administrators(785)
create_builtin_administrators: Failed to create Administrators
[2008/02/21 09:29:45, 0] auth/auth_util.c:create_builtin_users(751)
create_builtin_users: Failed to create Users

Please find below a par of the smb.conf:
 log file = /var/log/samba/log.%m
        load printers = No
        ldap ssl = no
        passwd chat = *Enter\snew\sUNIX\spassword:* %n\n
*Retype\snew\sUNIX\spassword:* %n\n *password\supdated\ssuccessfully* .
        include = /etc/samba/dhcp.conf
        socket options = TCP_NODELAY
        obey pam restrictions = Yes
        logon drive = C:
        force group = all
        deadtime = 15
        domain master = Yes
        winbind enable local accounts = no
        passdb backend = tdbsam
        passwd program = /usr/bin/passwd %u
        wins support = true 
        allow hosts = 10.64.1.0/255.255.255.0, 10.32.2.0/255.255.255.0,
10.64.7.0/255.255.255.0
        dns proxy = No
        domain admin users = root
        oplocks = no
        netbios name = PDC01
        server string = %h server
        writeable = yes
        logon script = %U.cmd
        remote announce = 10.32.2.255/DOMAINXX
        workgroup = domainxx
        force user = smbguest
        os level = 32
        add user script = /usr/sbin/useradd -d /dev/null -g 300 -c "Machine
Account" -s /bin/false -M %u
        update encrypted = Yes
        syslog = 0
        panic action = /usr/share/samba/panic-action %d
        max log size = 1000
        domain logons = Yes
        security = user


Anyone any clue on how to proceed to make this work? Thanks already.


With kind regards,
Johan Louwers