This is a great trick to play on someone if you can get physical access to their computer but I warn you, this requires regestry editing so there is a good change that you skrew up the computer.

Go into Windows Explorer and launch Regedit.exe from the Windows directory and go to:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer

In the right pane look for the NoClose Key. If it is not already there then create it by right clicking in the right pane and selecting New > String Value(Call it NoCloseKey ). Now once you see the NoCloseKey in the right pane, right click on it and select Modify. Then Type 1 in the Value Data Box.

Doing the above on a Win98 system disables the Shut Down option in the Shut Down Dialog Box. But on a Win95 machine if the value of NoCloseKey is set to 1 then click on the Start > Shut Down button displays the following error message: This operation has been cancelled due to restrictions in effect on this computer. Please contact your system administrator.

You can enable the shut down option by changing the value of NoCloseKey to 0 or simply deleting the particular entry i.e. deleting NoCloseKey. Instead of performing the above difficult to remember process, save the following with an extension of .reg and add it's contents to the registry by double clicking on it.

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer]

"NoClose"="1"