Password Change Problem on Active Directory

Hello,
I have experienced some problem on password change on client PC. We set the
password 90 days expired. By the way, When the user tries to change password
on client after seeing the message like " You have to change password as the
10 days remain until the ID lock", the user cannot change the password
saying the message "You are not autorized to change password". But before
seeing the message on client showing days left for expiry, user can change
the password without any problem.

Our system environment is follows;
Server : Windows 2000, Active Directory.
Client : Win XP.

Is there anyone who know the cause ?

Regards,