Screen flash disabled but happens anyway

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Level 1

1 points

Screen flash disabled but happens anyway

My Mac has started flashing the screen instead of beeping. It's exactly the same effect as you'd get if the Accessibility pref pane's "flash the screen" option was enabled, except that it's not enabled. The checkbox in System Preferences is not checked.

I also verified that the preferences property list file affecting this setting shows it as being off. In ~/Library/Preferences/com.apple.universalaccess.plist I see:

<key>flashScreen</key>

In case it makes any difference, the system sound is otherwise normal and not muted. I'm listening to music from iTunes, but getting screen flashes instead of beeps.

This happened a couple of weeks ago, and rebooting the Mac got things back to normal. Why does it keep happening? Is there something I can do to stop it from repeating again? The screen flash is going to give me a seizure.

iMac, OS X Mountain Lion (10.8.2)

Posted on Feb 22, 2013 11:46 AM

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Answer 1

Eric Root

Level 10

684,039 points

Feb 22, 2013 2:26 PM in response to Mechanist

Try setting up another admin user account to see if the same problem continues. If Back-to-My Mac is selected in System Preferences, the Guest account will not work.

Isolating an issue by using another user account

If the problem is still there, try booting into the Safe Mode. Shut down the computer and then power it back up. Immediately after hearing the startup chime, hold down the shift key and continue to hold it until the grey Apple icon and a progress bar appear. The boot up is significantly slower than normal.

Safe Mode

Safe Mode - About

General information.

Isolating issues in Mac OS X

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Answer 2

Mechanist Author

Level 1

1 points

Feb 22, 2013 2:46 PM in response to Eric Root

Eric-- Thanks for the suggestions. But after I boot into safe mode, then what? It took almost two weeks for the problem to recur. Rebooting normally will almost certainly clear the problem again-- for a while. I can't very well run in safe mode for weeks at a time. Is there something you suggest I do once I'm in safe mode?

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Answer 3

Eric Root

Level 10

684,039 points

Feb 22, 2013 5:18 PM in response to Mechanist

If it is a persistent problem, it should show in Safe Mode. Safe Mode also clears some stuff up, so it may eliminate the problem.

Not suggesting you run in Safe Mode for weeks.

Do a normal restart and see if the problem is still there.

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Answer 4

Mechanist Author

Level 1

1 points

Feb 22, 2013 5:20 PM in response to Eric Root

I only mentioned running in safe mode for weeks because (as I mentioned earlier) rebooting made the problem disappear for nearly two weeks. If I reboot again, I expect the problem will disappear again, for at least a while. I'd really like to stop it from coming back again, though.

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Answer 5

Mechanist Author

Level 1

1 points

Feb 25, 2013 1:30 PM in response to Mechanist

After a normal restart things are back to normal-- for now, at least. I'll see if they stay normal after a week or two.

I checked with a different account before restarting. In the other account I got no beep sounds at all-- no sound, but also no flash. I even loaded sound settings in System Preferences and clicked on different beeps, and just got silence. Sound was not muted, either.

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Answer 6

Eric Root

Level 10

684,039 points

Feb 25, 2013 2:29 PM in response to Mechanist

Something isn't right if you had no sound in the new account. If you continue to have problems, I suggest you try reinstalling Mountain Lion.

OS X Recovery

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Answer 7

Mechanist Author

Level 1

1 points

Feb 25, 2013 4:02 PM in response to Eric Root

I may end up doing that but reinstalling the OS has always seemed like the caveman approach, grabbing the biggest stick you can find and bashing on the computer until it works. Obviously something isn't right, but it would be really nice if I could figure out what it is and fix it.

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