[Samba] win password sync works, smbpasswd fails

[Stefan Froehlich]

Really odd behaviour on a Debian/Squeeze system: when users change
their password from within Windows, everything works fine (i.e.
passdb.tdb is updated and /etc/shadow as well via password sync, the
user can log in on both systems).

When I try to assign a new password via smbpasswd (or create a new
user, which causes the real problem), /etc/shadow is updated
properly (unix logins are possible), but users CANNOT login with
windows anymore (though the timestamp of passdb.tdb is updated, so
smbpasswd DOES something there). I have to reassign the old password
with smbpasswd and to change it via windows to re-enable login for
this user.

What can cause such a behaviour? I never had trouble in THIS
direction before - only the other way round... but what can make
smbpasswd store a wrong(?) password in its native database?

Lines of smb.conf I consider relevant:

domain master = yes
domain logons = yes
security = user
encrypt passwords = true
passdb backend = tdbsam
obey pam restrictions = yes
unix password sync = yes
passwd program = /usr/bin/passwd %u
passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .
pam password change = yes

If you need any more details, please ask.

Bye,
  Stefan