I updated an iMac 2011 to High Sierra and now the dock and the upper bar disappear continuously and the wallpaper turns black. Just for a second, then all restart again. And it is happening all the time. It's like the GUI is restarting but other apps don't.
Sometimes a note that said "In order to enable Apple-tab, the Dock must first be quit and relaunched. This will cause all minimized windows to be expanded. Do you wish to proceed?" appear, if I press "no" the problem stop until I restart the computer.
Any idea about how can I fix this?
Best Answer
I'd start by trying to reset the Dock first and then manually quitting and relaunching it. Note you will need to re-add any non-default icons (i.e. apps) that you've added to the Dock - so you may want to take a screenshot of your Dock as a reminder of what you had there. (Or start afresh and only add things as you actually use them).
Reset the Dock
To reset the Dock, follow these steps:
Quit and relaunch the Dock
To quit and relaunch the Dock, follow these steps:
killall -KILL Dock
Once you've done the above I'd restart your computer to see if the problem has been resolved. If it hasn't, then I'd try rebooting into Safe Mode to see if the problem is still present.
Boot into Safe Mode
Follow these steps to boot your Mac into Safe Mode:
Let me know how you go.
[EDIT]
Since you've established that you don't have the problem in Safe Mode, but still do after logging in normally again, then it's time to investigate login items, fonts, and kernel extensions
Investigating login items, fonts, and kernel extensions
Let's start with Login Items:
Now your Mac will boot up without those login items loading. Test this and see if the problem persists:
Fonts:- You can remove any of the fonts you've installed yourself to see if this makes a difference.
Kernel Extensions:- You can open Terminal (found within your Utilites folder) and enter the following command:
kextstat | grep -v com.apple
The above command will list 3rd party kernel extensions (you may need to stretch the Terminal window so it's easier to read). Look for anything you don't remember installing, or something that belongs to software you've removed, or just anything that looks out of place. Remember though, this is a list of 3rd party kernel extensions and therefore any of them could be causing the problem.