Difficult to describe exactly what happened, but best as I can...

  • Mac Pro 08 running El Capitan; all else up to date.
  • Plugged iPad into a USB cable coming via the wired keyboard.
  • Mac screen went entirely black. Mouse cursor was still active, but no keyboard input would be accepted - any command would give the 'oops, wrong key command' beep.
  • As far as I could tell, all apps were still running correctly, behind the scenes, though the only real evidence was that the internet radio was still playing in Safari.
  • Unplugging the iPad made no difference.

  • Prime consideration - I didn't want to hard power-off the Mac, risk losing work &/or [this has happened before] not being able to boot up until I'd fiddled with Disk Warrior/TechTool etc

Incidentally, the iPad shows as Not Charging. I haven't yet investigated whether this is because it's connected through the keyboard rather than directly.

I need to do further research to see what may have been the cause, but I'm going to post an answer myself as to how I got out of the black screen, in case it's useful to others...

1 Answer 1


Because I didn't want to hard power-off the Mac I had to do a bit of lateral thinking.

I was quite sure that the machine hadn't actually hung, as the radio was still playing, but that perhaps something had upset the Finder, which I think was the frontmost app at the point the iPad was plugged in.

A moment of revelation... what about dialling in remotely?

I went to my other Mac & tried to get in via Screen Sharing.
Success... or not... I could share the screen, but it was still black with just a working cursor.

What if I try to login as myself instead?

Screen Sharing showed me the login screen.
I went to check the remote machine, it too was showing the login screen.
I logged the original user back in, rather than myself, & we were up & running again.

I rebooted at that point, normally, & the issue hasn't recurred.

I still have no explanation as to what caused it, but I hope this might help anyone else who sees a similar issue.

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