samba - May 2009 - 2003 server member of a SMB3 domain

Hi all

I am facing the following issue :

I 've just installed a fresh windows 2003 server and want to add it to a
samba 3 domain.
netbios is ok on windows, I can log onto the smb server shares... but if I
try to add the 2003 server to the domain it echoes the an error saying that
the PDC for the domain XXX (netbios domain format, not dns) can't be found.

I don't understand why because I have another 2003 server which has joined
the smb domain without any issue some month ago.

client : windows 2003 SP2 (not R2)
server PDC :  Version 3.2.7

global part of smb.conf below :

        workgroup = xxx
        netbios aliases = yyy01
        server string = yyy01
        allow trusted domains = No
        passdb backend = tdbsam:/etc/samba/passdb.tdb
        passwd program = /usr/bin/passwd %u
        username map = /etc/samba/smbusers
        unix password sync = Yes
        log file = /var/log/samba/%m.log
        log level = 1
        max log size = 50
        announce version = 6
        name resolve order = wins lmhosts  host bcast
        time server = Yes
        socket options = SO_KEEPALIVE SO_REUSEADDR SO_BROADCAST TCP_NODELAY
IPTOS_LOWDELAY IPTOS_THROUGHPUT
        load printers = No
        add user script = /usr/sbin/useradd -m %u
        delete user script = /usr/sbin/userdel -r %u
        add group script = /usr/sbin/groupadd %g
        delete group script = /usr/sbin/groupdel %g
        add user to group script = /usr/sbin/groupmod -A %u %g
        delete user from group script = /usr/sbin/groupmod -R %u %g
        add machine script = /usr/sbin/adduser -n -g grp_machines -c
grp_machines -d /dev/null -s /bin/false %u
        logon script = logon.bat
        logon path = \\%L\Profiles\%u\%m
        logon home = \\%L\%u\.win_profile\%m
        domain logons = Yes
        os level = 255
        lm announce = Yes
        domain master = Yes
        preferred master = Yes
        remote announce = 172.27.137.255
        bind interfaces only = True
        interfaces = eth0 172.27.137.201
        wins support = Yes
        ldap ssl = no
        default service = global
        idmap uid = 16777216-33554431
        idmap gid = 16777216-33554431
        winbind enum users = Yes
        winbind enum groups = Yes
        winbind use default domain = Yes
        winbind trusted domains only = Yes
        admin users = ase, smb-adm
        cups options = raw
        host msdfs = Yes
        msdfs root = Yes
        deadtime = 60




any help?

thanks
regards