I'm running Snow Leopard 10.6.8. I leave my machine for an hour. When I return the machine is asleep and all the applications have been shut down. It is almost as if it has spontaneously restarted.

Any ideas what could be causing this?


2 Answers 2


I'm not sure what is causing it, but it sounds like a hardware issue, or that the power outlet the machine is plugged into may be faulty.

You can try going to the Energy Saver preference pane and unchecking Start up automatically after a power failure. If the computer really is shutting down and restarting this may help you find out.

If it is shutting down, it may be:

  • Faulty power supply
  • Faulty power outlet or another electronic device complicating power in that outlet
  • Overheating
  • I don't see this option on Snow Leopard. Jun 20, 2012 at 11:27

If you are running Lion, you may be seeing the effects of Lion's auto kill feature. This feature automatically quits any applications that are open if they haven't been used in awhile. Try disabling it as such by typing this in Terminal:

defaults write -g NSDisableAutomaticTermination -bool yes

To turn it back on:

defaults write -g NSDisableAutomaticTermination -bool no

From this answer.

  • Could this be on Snow Leopard too? May 21, 2012 at 15:43
  • @EricBrotto No. Snow Leopard did not have auto kill.
    – daviesgeek
    May 21, 2012 at 15:48

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