We have AD Server in our office and after removing network connection user can login with AD Authentication with their own desktop and data so kindly tell me how this can happened?
I think this will help you understand that feature:
<a href="http://support.microsoft.com/kb/913485">Cached credentials security in Windows Server 2003, in Windows XP, and in Windows 2000</a>
Last Wiki Answer Submitted: April 13, 2010 2:04 pm by carlosdl63,580 pts.
If you live outside the United States, by submitting your email address you consent to having your personal data transferred to and processed in the United States.
Sounds like they have cached profiles / credentails, or they have been made a local adminstrator of the machine.