samba - Jul 2010 - Add user script executed after PDC authentification failed

Hello,

I've got a recent problem when upgrading my PDC from 3.0.x to 3.5.3.

When a fileserver (samba 3.0.x configured as security=domain) is contacted
by a new non domain user (here I used "localuser1"), the fileserver
invoke
the add user script although the PDC does not authenticate that user.
Prior to the PDC samba upgrade the local users were not created and this is
the behaviour I want to conserve.

My PDC logs :
[2010/07/26 12:58:24.127634,  2] auth/auth.c:314(check_ntlm_password)
  check_ntlm_password:  Authentication for user [localuser1] -> [localuser1]
FAILED with error NT_STATUS_NO_SUCH_USER

Could someone help me?