are you sure you want to quit all applications and log out now?

In the "Security and Privacy" preference pane click the "Advanced..." button and uncheck "Logout after XX minutes of inactivity"

I found this problem after I installed OS 10.11.

Short Answer:

System Preferences > Security & Privacy > General > Advanced

Long Answer:

1. System Preferences

2. Go to tab: Security & Privacy

3. In the bottom left corner of window click on padlock & enter your password.

4. Click the General button (it is the default setting)

5. In the bottom right corner of the window you will see the "Advanced" button.

6. Click the Advanced Button.

7. Uncheck the square "Log out after..." Or change the minutes of inactivity.

8. Click "OK" and exit System Preferences.

Happy to help.

You might be able to fix it by resetting the System Management Controller (SMC). If not, make a "Genius" appointment at an Apple Store to have the machine tested.

Back up all data on the internal drive(s) before you hand over your computer to anyone. If privacy is a concern, erase the data partition(s) with the option to write zeros* (do this only if you have at least two complete, independent backups, and you know how to restore to bare metal from any of them.) Don’t erase the recovery partition, if present.

*An SSD doesn't need to be zeroed.

🙂🙂🙂 THANK YOU, Tim!!!!

I am adding to this thread as I am having this issue on my mid 2011 iMac running Sierra 10.12.5

My issue goes a little further than what is stated here.

If I let the computer 'sleep' and log back on I see this message (are you sure you want to quit all applications and log out now...) and then it will proceed to countdown and shut the computer down. Why is this question appearing when I log back on?

I have tried every recommendation outlined on this page and yet still have the issue UNLESS I uncheck the item under the advanced menu which I am not sure I should have to do as it is a security option that allows me to walk away from my workspace.

As it is now, I am so paranoid that I log myself off or put the computer to sleep before walking away.

It just doesn't make sense.

thanks for any input.

Thank you! I'm not sure why this would have ever been turned on, or even an option for that matter!

Wow! That did the trick! You saved me from doing a clean install.

Hey Tim,

You solved the mystery that has been confusing me for the last 1 year! Thanx!