User can't change password

I have just built a new domain controller from the ground up. I have set up all of my users with one default password and I clicked the box to make them all have to change their password at the next logon. When the client tries to logon, it says that the password has expired and to change it but once they try, they get "You do not have permission to change your password" I have group policy set up but there are no password policies yet. Also, the only groups that they are part of it Domain Users but even when I add a user to the Administrators group, they can't change their password either. Please help. Thanks, Jeremy