My screen gets tunnel vision

Question

My MacBook Air froze up a few times.  The screen went dark with a faint image in the center.  It was as if it was in sleep mode, but I could not wake it up.  I played with the brighten buttons (f1 and f2) and it eventually woke up.  The screen sometimes changed when the computer woke up.  The curser was working even though I could not see what it was on, so it would sometimes change the screen by clicking something I couldn't see.  Is this a glitch?  Did I inadvertently change a setting?  Has this happened to anyone else?

Answer 1

Hi slowplodding,
Thanks for visiting Apple Support Communities.
If your display goes dark or your computer seems to sleep unexpectedly, I recommend first trying the steps in the "Additional troubleshooting" section of this article:
OS X: When your Mac doesn't sleep or wake
http://support.apple.com/kb/TS5357
Reset SMC
The System Management Controller (SMC) is involved in managing power on your computer. Reset the SMC on your Mac if you are having difficulty sleeping or waking your computer.
Reset NVRAM/PRAM
Nonvolatile RAM (NVRAM)/Parameter RAM (PRAM) stores some power-related settings.Try resetting NVRAM/PRAM if you are having difficulty sleeping or waking your computer.
Test with external devices disconnected
Some external devices can prevent your computer from sleeping. Try disconnecting items other than your Apple keyboard or mouse from the built-in USB, Thunderbolt and Firewire ports on your Mac. If this resolves the issue, try reconnecting your external devices one at a time until you find the device preventing sleep or wake. Check the documentation that came with the device, or contact the device manufacturer for more information.
Try Safe Mode
Check to see if the issue still occurs when the computer is started in Safe Mode. If this resolves the issue, it could be related to a third party software item such as:
a login item
a startup item
a third party kernel extension
Try another user account
Try creating another user account, or log in as guest. See if your computer sleeps and wakes properly from the additional user account. If it does, your issue may be related to one of the following:
a login item
an app open in the original user account
You can disable login items from the Accounts pane of System Preferences. Try opening only one app at a time in the original user account to determine which app is preventing sleep. If you isolate the issue to a particular app or login item, check its documentation, or contact the developer of that software for more information.
Cheers,
Jeremy