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Posted By: grelber Screen going black - 07/05/12 10:21 PM
And add to that the screen's going black when the cursor is dragged through the dock ... and comes back to life when dragged back again.
Mystery upon mystery.
Posted By: Virtual1 Re: Screen going black - 07/05/12 10:28 PM
Originally Posted By: grelber
And add to that the screen's going black when the cursor is dragged through the dock ... and comes back to life when dragged back again.
Mystery upon mystery.

mmm can't say I've ever seen that happen before. related? or needs a new thread?
Posted By: grelber Re: Screen going black - 07/05/12 11:29 PM
It only happens occasionally, and I can't replicate it "on purpose".

As for a new "mystery gesture" thread ... it makes me no never mind. Just thought it might be useful to put such weirdness together in one spot.

EDIT: Actually, the screen doesn't go "black", just extremely dark, but one can see what is there very dimly.
Posted By: Virtual1 Re: Screen going black - 07/05/12 11:48 PM
Originally Posted By: grelber
Just thought it might be useful to put such weirdness together in one spot.

You unlock this door with a key of imagination. Beyond it is another dimension - a dimension of sound, a dimension of sight, a dimension of mind. You're moving into a land of both shadow and substance, of things and ideas. You've just crossed over into… the twilight zone.
Posted By: MicroMatTech3 Re: Screen going black - 07/06/12 01:06 AM
Willoughby, next stop Willoughby.
Posted By: grelber Re: Screen going black - 07/06/12 08:44 AM
Ah yes ... such weirdness does bring out the channelers of Rod Serling.

[See EDIT in my last post.]
Posted By: artie505 Re: Screen going black - 07/06/12 09:04 AM
> Actually, the screen doesn't go "black", just extremely dark, but one can see what is there very dimly.

That's the same thing you'll see if you turn your screen brightness down to its lowest possible setting.

I'll suggest that you run Apple Hardware Test, although I don't know what, if anything, it may tell you.

For more ideas you'll have to wait for more of America to awaken.
Posted By: grelber Re: Screen going black - 07/06/12 09:50 AM
I doubt that it would tell me anything, since it only occurs sporadically under the conditions noted.
I've checked various System Preferences for anything which might have been inadvertently checked, but nothing out of the ordinary pops up.
Posted By: ganbustein Re: Screen going black - 07/07/12 07:33 PM
Originally Posted By: grelber
And add to that the screen's going black when the cursor is dragged through the dock ... and comes back to life when dragged back again.
Mystery upon mystery.

Maybe the trigger isn't so much dragging the cursor through the dock as dragging it into a corner. Each of the four corners of the screen can be configured as a "hot corner" to trigger actions like "Put Display to Sleep" (makes screen go black), "Start Screen Saver" (possibly likewise, depending on your choice of screen saver), or "Desktop" (move windows off-screen and put a gray border around the now-exposed desktop).
Posted By: artie505 Re: Screen going black - 07/07/12 08:15 PM
When I use my "Put Display to Sleep" hot corner my display blackens with no desktop image visible behind the black, as opposed to grelber's description of what he is seeing:

Originally Posted By: gelber
Actually, the screen doesn't go "black", just extremely dark, but one can see what is there very dimly.

Since that's precisely what I see when I turn my screen brightness down to -0-, I suggested a possible hardware issue, but grelber is disinclined to run Apple Hardware Test (again, not that I've got the least idea whether it will find anything).
Posted By: grelber Re: Screen going black - 07/07/12 09:14 PM
Nope. It has nothing to do with corners. And, as noted, all such possibilities have been ruled out.
Posted By: grelber Re: Screen going black - 07/07/12 09:24 PM
I don't know what Apple Hardware Test is. It certainly didn't come with my iMac or Lion ... at least not so I can find it. It's not mentioned in Pogue's Missing Manual.
Posted By: artie505 Re: Screen going black - 07/07/12 09:34 PM
See Intel-based Macs: Using Apple Hardware Test. (I can't imagine Pogue having overlooked it.)

Although I doubt that it will tell you anything more than "Nothing" (which, in and of itself, is something), I'll still recommend that you run the extended test.
Posted By: grelber Re: Screen going black - 07/08/12 08:26 AM
I have scoured Pogue's manual and find no reference to AHT in any form. I'll consider this approach if the problem surfaces again.
Posted By: artie505 Re: Screen going black - 07/08/12 10:28 AM
> I have scoured Pogue's manual and find no reference to AHT in any form.

That's odd; have you looked in "Help" on your iMac?
Posted By: grelber Re: Screen going black - 07/08/12 03:29 PM
Yes. Spotlight shows up nothing related. Help Center shows up nothing either on or off line; of course, Help Center online never loads — it seems to want broadband interaction.
Posted By: artie505 Re: Screen going black - 07/08/12 04:49 PM
Originally Posted By: grelber
Yes. Spotlight shows up nothing related. Help Center shows up nothing either on or off line; of course, Help Center online never loads — it seems to want broadband interaction.

Bizarre! (That's on my MacBook, not on line/OS X 10.6.8.)
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