Recently I was puzzled by a Macbook Pro that was going to sleep and shutting down applications after 10 minutes off inactivity. Even "Mouse Jiggler" or iTunes visualizer would not keep this Mac awake!
This was causing a real problem since Time Machine could not finish its back-up. Neither could I run my tools to do a OS X system cleanup and tuneup.
I checked these settings in System Preferences:
- Energy Saver Settings
- Desktop and Screen Saver
- Security and Privacy > General
I also zapped various p-lists, rebooted the system etc etc.
Still the Macbook kept locking up after 10 minutes of inactiviry. :-(
Next step was the reinstall 10.7 Lion or even upgrade to 10.8 Mountain Lion. To avoid a catastrophic data loss on my clients computer I needed to image all the data to a secure drive first. Adding an other 3 hours to the repair time.
I went one more time back into the system preferences and had a deeper look. There it was right in front of me:
System Preferences > Security & Privacy > General > Advanced
Uncheck the box "Log out after 10 minutes of inactivity
I still upgraded to Mountain lion and did a System Tune-Up and manually re-arranged some data to complete the job.