Per-machine Group Policy, and security group membership for both users and computers, is only processed during the initial startup/login process. You can trigger re-evaluation of computer group membership however by using the Klist command, which is part of the Windows Server 2003 Resource Kit Tools, by running the following command:
klist –li 0x3e7 purge
Then run this command on the computer:
The first command clears the Kerberos ticket cache for the computer account (that’s the 0x3e7 part) while the second command causes the computer to authenticate anew and determine its new group membership.
The Windows Server 2003 Resource Kit Tools can be downloaded from http://go.microsoft.com/fwlink/?LinkId=77796
Mitch Tulloch is a Microsoft Most Valuable Professional (MVP) and widely recognized expert on Windows administration, deployment and virtualization. For more tips by Mitch you can follow him on Twitter or friend him on Facebook.