I often add the servers computer account to an Active Directory Group. And as we all know you have to boot in order to update this group membership. Or maybe not?? In order to update group membership without rebooting you need psexec or another method of starting a CMD as system. Start psexec –s cmd . Verify using whoami command to see that you are running as system. Then you type:
klist is a kerberos command for viewing and purging cached kerberos tickets. After you have purged it the membership will be updated the next time you try to access something that requires that membership.
Information about klist can be found here: http://technet.microsoft.com/en-us/library/hh134826(WS.10).aspx