Create a batch file with this one line:

@exit

Create a shortcut to it on the Desktop, right-click it, and choose Properties from the menu. In the Program tab click the Advanced button, check the MS-DOS mode box, then Warn before entering MS-DOS mode (if you want the confirmation, that is; chances are you don't really want to check this).

Upon activating the batch file, Windows will quickly close, then reboot the computer.