7KerberosThe kerberos subsystem encountered a PAC verification failure. This indicates that the PAC from the client computername$ in realm DOMAIN.LOCAL had a PAC which failed to verify or was modified. Contact your system administrator.
This error appeared on a Windows XP workstation (SP2) in a Win2k3 domain. The workstation had not been rebooted in a while, and rebooting the workstation solved the problem.