samba - Apr 2004 - Strange message while trying to change pass from windows XP

Hi
I configured samba as a PDC of my domain (LDAP backend).

Everything is working flawlessy except the password change (with 
ctrl+alt+suppr) under winXP.

When I try to change pass, the system complains about incorrect password 
(case) although the password is effectively modified....


Any clue to make this ugly message not to appear?

Thanks