Windows NT 4.0 Service Pack 4, offers an option for an immediate system reboot.

If your press Shift+Ctrl+Alt+Delete, the system will stop all running apps, without saving any inprocess data, and reboot your computer. Event ID 6008, The previous shutdown at <HH:MM> on <date> was unexpected., will be posted to the System Event Log.

To activate this option, navigate to:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Winlogon

Add Value name EnableQuickReboot as a type REG_SZ entry and set the text string to 1 (true).

You must restart your computer for the option to become available.