Any user can add workstation to Windows Server 2003 domain even with GPO set
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  As the title says - we have a domain with a DC running Windows Server 2003 that is allowing any authenticated user to add workstations to the domain.  Currently in the Default Domain Policy, we have configured it to only allow Administrators to have this ability (also, this policy is applied to Authenticated Users):

Windows Settings -> Security Settings -> Local Policies/User Rights Assignment -> Add Workstation to Domain:  BUILTIN\Administrators, DOMAIN\Domain Admins

  What did we miss, or how might it be misconfigured to keep allowing any authenticated user to add workstations to the domain?

  Thanks in advance for the help.