With Windows XP, Vista, 7, and Windows Server 2003 and 2008 you now cannot shutdown the machine from the Start button when you are logged in via Remote Desktop (RDP). To reboot the server run:
shutdown -t 0 -r -f
If you want to just shut it off, run (notice that -r is missing, this means it will not be rebooted):
shutdown -t 0 -f
The “-t 0″ tells the system to wait zero seconds be shutting down or rebooting. You can change the zero to any number of seconds you want. The “-f” tells the system to not prompt for confirmation. So make sure you really want the server shut down or rebooted.
There are other options that you can use, you can see all the options on the Microsoft site here
