My wired mac keyboard is acting weird. Some keys perform weird extra insertions. The problem introduced itself when I relogged in after sleep mode and persists since then. The internal MacBook keyboard is not affected. I suspect some corrupted driver settings/files.

I tried the following already, without change:

  • login with a different user
  • restarting the mac
  • dis-/reconnecting the keyboard

Some of the extra insertions happening:

  • u => u[
  • 7 => 7-
  • return => creates a new line and an *
  • m => m and a space character
  • j => j'
  • right arrow => performs a return

I am on OS X 10.9.5

Edit: I plugged the keyboard into a Windows machine, same problem. So it's a hardware issue ... or is it? Is it possible that the keyboard firmware is somehow corrupt? Since many keys are acting strange and not ONE key that's broken.

Can I reset the keyboard firmware?

  • What is "Fritz" ?
    – Ruskes
    Nov 1, 2014 at 18:58
  • being on the fritz means acting weird, updated the question.
    – owzim
    Nov 1, 2014 at 19:03
  • 1
    I know that, the question is what keyboard layout is selected in sys pref keyboard? try changing it to US Extended to see.
    – Ruskes
    Nov 1, 2014 at 19:11
  • 1
    Have another computer you can connect the keyboard to? Might possibly be the keyboard has a fault in it.
    – douggro
    Nov 1, 2014 at 19:40
  • 1
    So what keyboard type is it ? it is not the driver but did someone spill stuff on it? did you try the usual mechanical cleaning- blowing ect ?
    – Ruskes
    Nov 1, 2014 at 20:33

1 Answer 1


I ended up carefully removing all the key caps (like shown here http://www.youtube.com/watch?v=G_Cue2IlXIg) and cleaning up the dust/dirt that accumulated over the past two years. I guess it messed with the electronic contacts.

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