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December 11th, 2014

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As of 2015-04-08, Apple has released an update, 10.10.3, that seems to fix this problem. The iSchool IT department recommends, that if you are using OS 10.10.0, 10.10.1, or 10.10.2, you update to 10.10.3. The update is available in the App Store:

1) click the upper-left Apple icon
2) click App Store…
3) click Updates

The update process takes around 15 minutes, so, pick a time when you will not need your computer for a short time.


There appears to be an issue with the latest version of the Mac OS X operating system, 10.10.X, commonly referred to as Yosemite. Sometimes, after the computer enters Sleep mode, it will become unresponsive, need to be rebooted, and the computer gets stuck during start up.

This problem is not confined to iSchool issued Macs. Rather, it seems to be an issue with the Apple operating system itself.

If your computer gets stuck at the grey loading screen with the Apple logo with the progress bar underneath:

Apple Logo Boot Screen

First try a PRAM reset (

  • Power off your computer (press and hold the power button if necessary).
  • Power on the computer.
  • Immediately press and hold the option + command + P + R keys. You must press this key combination before the gray screen appears.

Continue holding the keys down until your Mac restarts, and you hear the startup sound for the second time.

  • Release the keys.

From our experience, you may have to do the above steps multiple times.

If that does not help, the second thing to try would be a safe mode start (

  • Power off your computer (press and hold the power button if necessary).
  • Power on the computer.
  • Immediately after you hear the startup tone, hold down the shift key.

You should press the shift key as soon as possible after you hear the startup tone, but not before.

Release the shift key when you see the gray Apple logo and progress indicator.

  • Exit safe mode. Restart your computer but don’t hold down any keys during startup.​

Of course, if your computer does not start up, you might not have access to these instructions. You may want to print out these instructions for future reference.

If neither option helps, please contact the iSchool IT Help Desk.

If you have any questions after reading this article or if you need any help, please don't hesitate to contact the iSchool IT Help Desk.
(206) 616-3086