Multiple user screen freezing.

[tunerX]

I have two iMacs a 27 inch late 2009 and a 27 inch late 2014.

Initially I thought it was a problem with the 2009 only (I was thinking graphics card). During some random event(clicking a link, going to a web page, opening a document)will lock up the screen. I can move the mouse pointer around but nothing works. When the screen blacks out I can use the mouse or keyboard to get the backlight on but just get a black screen with backlight. I didn't suspect it was related to multiple user accounts until my wife wanted to add kids accounts to the 2014 iMac.

After she added some kids accounts she started experiencing the same thing.

If a single user is logged into either system it can run without any problems. Once an additional user logs in it is a just a matter of some random event causing lockup of the screen. Then I am forced to do a cold boot.

I have had this problem with Mavericks and Yosemite on the 2009 and with Yosemite on the 2014. I haven't updated either system to El Capitan yet.

 

[JJayguy23]

Maybe try NVRAM reset. Restart computer, Hold Down CMD-OPTION-P-R while computer resets. This should help with hard to troubleshoot issues.

Source:
https://support.apple.com/en-us/HT204063

 

[tunerX]

I tried the PRAM and the SMC before. It still does the same thing afterwards.

 

[997440]

I came across this at ASC -- A user had a wake issue and 'cured' it by deactivating screen saver in all accounts. Might be worth a try and also see what the sleep settings are in each account.
https://discussions.apple.com/message/26077949#26077949

 

[tunerX]

I came across this at ASC -- A user had a wake issue and 'cured' it by deactivating screen saver in all accounts. Might be worth a try for that and to see what the sleep settings are in each account.
https://discussions.apple.com/message/26077949#26077949

I just disabled screensaver for all accounts and will see if it helps. Thanks for a possible solution.

 

[tunerX]

I came across this at ASC -- A user had a wake issue and 'cured' it by deactivating screen saver in all accounts. Might be worth a try and also see what the sleep settings are in each account.
https://discussions.apple.com/message/26077949#26077949

It is still happening, but it went from more than once a day to once every couple of days.

 

[997440]

It is still happening, but it went from more than once a day to once every couple of days.

To be clear -- I'm new to OS X. It sounds to me that your issue is either an OS X bug or, even though you're experiencing it on two different machines, an install issue. Maybe someone more experienced will chime in with a suggestion.

Working under the assumption that whatever you've recently done with the screen saver preferences have resulted in the changes you report -- Have you also changed all energy saver related settings in each account pertaining to sleep? I'd try to set the different settings for sleep to *don't* and also to not automatically turn any monitor off.

 

[tunerX]

I found part of the issue and now I am puzzled. It is related to Safari. I re-enabled all of the screensaver settings because that didn't seem to fix anything. If multiple users have Safari running it can lock up at what seems like random.

I switched to google chrome and have been running for a week without a single freeze up on either computer. Finding the problem seems like it will be too time consuming, because when a different user is using it, I am not there. And asking kids to take note of every single thing they are doing and clicking on and leaving open in different tabs is like herding cats.

 

[997440]

If you find the time and if you have parental controls set, try disabling them. Could be some type of setting there or conflict that's the cause. I searched for parental controls issues after you mentioned kids again and that you've had some success with Chrome. Plenty of hits including security software conflicts.

Also, if you can cause the issue, check the console for any clues. Good luck.