Key: Software\Microsoft\Windows NT\CurrentVersion\Winlogon
Value: 1 Yes
Value: 0 No
Note: some Microsoft documentation lists this as REG_DWORD. That is incorrect. It is REG_SZ in NT, W2K and XP. ShutdownWithoutLogon can also be set by GUI tool, RegKey.exe from the Resource Kit. From a security perspective, not particularly useful unless the power switch is also secured. Another approach is to remove the user right Shutdown the system. By default workstation setups grants this right to Everyone, Users, and Power Users as well as Administrators.