Early 2011 15" Macbook Pro, Lion, no external keyboard or mouse:

Lately I noticed that I can't use left-shift+left-command together; it registers as left-command only. The other three combinations (right-shift+right-command, right-shift+left-command, left-shift+right-command) work properly. I’ve confirmed this in text editors and in the keyboard viewer.

Same problem appears with left-command+left-control.

I’ve shut down all programs, verified no weird keybinds in Universal Access or elsewhere, even installed Lion to a clean external disk and booted from that. The first thing I did was check left-shift and left-command in TextEdit; same problem.

Any ideas?

  • same problem... did you eventually figure it out?
    – Lena Bru
    Commented Aug 3, 2014 at 19:44
  • I'd forgotten about this question, saw the notice on my profile, checked, and the problem is gone. In the meantime I've reinstalled, upgraded to Maverick, and moved from the midwest to the west coast. If anyone happens to test those three in isolation please report back!
    – wilee
    Commented Aug 5, 2014 at 22:04
  • this problem started a week ago, and i was already a maverick user for a few months before it happened. I live in Israel..... I doubt your geographical location has anything to do with it.
    – Lena Bru
    Commented Aug 6, 2014 at 6:51
  • I suppose you've checked related answers, but does anything in this help? apple.stackexchange.com/questions/23775/…
    – wilee
    Commented Aug 18, 2014 at 17:12

1 Answer 1


I'm posting the non-answer of "I reinstalled OSX and upgraded to Maverick from Lion, and it now works" because, well, it now works. Unfortunately I don't know what were the actual reasons it broken and then un-broken. I am sorry to anyone whom this question didn't help at all.

If anyone else comes up with a reasonable explanation I'll mark them as the answer instead.

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