How can I force GPO updates to take effect?

A. Policies are refreshed every 90 minutes (5 on DC's). To forcea machine to update the policy use the SECEDIT command.

To update the computer policy type

C:> secedit /refreshpolicy machine_policy

To update the user policy type

C:> secedit /refreshpolicy user_policy

Adding /enforce to any of the above forces a  reapply of the security policy even if there is no GPO change.