Computer games

Dear computer and operating systems manufacturers: Why do all your products on some occasions fail to turn off when told to do so? In both Windows and Mac, I have closed the machine down and then come back later to see it's still on. Usually it's some program that wants to know if you really want to close it. My solution: A "save and close" button on the keyboard that saves everything and shuts the computer down no matter what, so one can safely walk away without fear of wasting any more electricity.