Having trouble with OSX on a MacBook Pro.

My system randomly locks up, becoming completely unresponsive to mouse or keyboard, then after a few seconds shows the OSX login screen, at which point it is responding to the mouse and keyboard again. There doesn't seem to be any specific thing causing it, from what I can tell.

I was wondering if this has happened to anyone else and if so do they know how to fix the issue?

If there is any commands that I can run to give more information please let me know. If it happens again I'll be trying to record it to put up on youtube.

Bought from apple site in April 2013 so not an old one.


2.9 GHz Intel Core i7
8GB 1600MHz DDR Ram
Intel HD Graphics 4000 512 MB
OSX 10.8.4 (12E55)


Updated with the log from is happening a few minutes ago.

  • Can you please have a look at /var/log/system.log and add the relevant part from around the moment you run into the issue to the question?
    – nohillside
    Aug 2, 2013 at 14:31
  • The first log entry includes "Invalid connection"... I'd guess that Google Chrome is failing to connect with the window server at that point, because the window server has died. So the problem started before that point. Can you post some earlier logs? Also: consider booking a Genius appointment at an Apple Store if you can -- perhaps they could run some diagnostics for you.
    – Ashley
    Aug 3, 2013 at 20:12
  • What are you running in Google Chrome? It's probably not Chrome per se but it might trigger something else which then kills the session.
    – nohillside
    Aug 19, 2013 at 9:26
  • I generally have gmail, github, stackoverflow and a few other tabs open. Sometimes youtube. It is also happening on a few of my colleges machines, would it be a network thing? Don't think there is anything specifically in chrome that triggers it.
    – Nalum
    Aug 19, 2013 at 9:58
  • Sounds like your LoginWindow.app might be crashing. You might want to look at your startup items and see if something is running that might be causing it to crash. (System Preferences -> Users & Groups -> Login Items )
    – Mark Cohen
    Aug 20, 2013 at 21:28

1 Answer 1


I have experienced similar problems with my MacBook Pro when I drop my earphones near the left side of my keyboard. I believe the MacBook uses magnets to detect the screen lid is closed, so when the magnetic field of the earphones get near the Macbook case it thinks the screen was closed and locks the system.

I have ever since placed my earphones somewhere else, far from the MacBook case and never had this problem again.

Check if you don't have any strong magnetic fields near your computer, even if a bit far from it.

  • Interesting but unfortunately not what is causing my problem.
    – Nalum
    Aug 21, 2013 at 15:12

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