Strange Wired Mac Keyboard behavior 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?
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.