In some situations and on some computers you may want to prevent computers from being shut down without your agreement. This could be in the following situations: - a public machine - a server which has an open session in an unsecure location - etc...
This is how you can disable the "Shutdown" button
Click on "Start", "Run..." and then enter "regedit" and click on "OK". Go to the following key:
Add a new DWORD value named NoClose and give it a value of "1" in the values data field
You can also download this reg file which will make the change for you!
The next time you reboot you will no longer see the Shutdown or Restart your computer option.
To reactivate this possibility or reboot your computer you simply need to delete the NoClose key that you created.
If you have deleted the NoClose key and want to return to "normal", you will have to press CTRL+ALT+Del to be able to shut down or reboot the system safely. This will only need to be done once as everything will then return to normal.