I cannot logoff or shutdown using the Start> shutdown or Start> logoff, nor by using CRTL_ALT_DEL. Neither by using the offered shutdown and restart option having made some change that the system detects needs a shutdown to activate. Neither by using the logoff utility in the Windows 2000 Resource Kit. Using Start>shutdown, the "Are you sure" dialog comes up, but selecting yes does nothing. The system continues to run as normal with no messages, no errors. At first I thought it only affected a user with Administrator privilege, but in fact it seems to randomly affect several profiles, regardless of privilege level. From a cold boot, generally it seems one logoff or shutdown is permitted and then the problem kicks in. The only way to shutdown or logoff is to remove the mains power supply and pop the battery out. Am running 2000 SP4 on a Dell C600 laptop.