Active Directory- problem creating new user

Hi,
I am facing problem to create a new user in active directory on server 2003. When I create a new user with the login and password then first time that users can login from client PC but the second time he can not login and screen shows the "method you are using is now allowed".
My client PC has windows vista business. Local policy of client PC has admin, user, guest but when I have connected to domain than I have seen it local policy has only admin no user and it did not highlight the add button so that I can add a user. Can any one help me what is wrong with my active directory user setting.
Thank you.
