OS X Mountain Lion: If you think you have incompatible login items
Login items are apps that open automatically when you start up or log in to your computer. Occasionally, a login item may cause a blank blue screen at startup or other problems.
- Shut down your computer, wait 30 seconds, and then hold down the Shift key while pressing the power button.
- When you see the gray Apple logo and progress indicator (looks like a spinning gear), release the Shift key.
- If you are prompted to log in, type your password, and then hold down the Shift key again as you click “Log in.”
- Choose Apple menu > System Preferences and click Users & Groups.
- Click your account’s name, and then click Login Items.
Make a list of the login items—you’ll need to remember them later.
- Select all of the login items and click Delete (-).
- Choose Apple menu > Restart.
If this solves the problem, open Users & Groups preferences again and add the login items one at a time, restarting your computer after adding each one, until the symptom occurs again. You don’t have to hold down any keys when you restart after adding each login item.
When you’ve found the incompatible login item, use the procedure above to remove only that item.