User Unable to change their Password

Hi,

Our domain user are not able to change their password ,In every three months user password expired & whenever user try to change it,it shows the system cannot change your password because the domain <domain Name> is not available error ,but if he login then press ctl+alt+del then he able to change the password. We are using 2003 server.All users have dynamic IP Setting.

I tried static ip & http://support.microsoft.com/kb/837327 but nothing works for me