Keyboard not typing, but responds to key commands

For the past week or so I've been having a weird issue occur when typing on a wired Apple extended keyboard connected to a Macbook Pro running 10.10.3.

The keyboard stops typing characters, requiring me to quit the app I'm using and re-open it for the keyboard to once again continue typing. But, to quit out of the app, I am able to type Command Q and it quits without a problem. So the keyboard is communicating with the computer.

Any ideas on what could be causing this?

Which MacBook Pro do you have: year and model? And how old is the wired Apple keyboard? The reason for the questions is there are two models of Apple wired keyboards, one is compatible with all Macs, the other is only compatible with Macs 2010 and later.

chscag said:

Which MacBook Pro do you have: year and model? And how old is the wired Apple keyboard? The reason for the questions is there are two models of Apple wired keyboards, one is compatible with all Macs, the other is only compatible with Macs 2010 and later.

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MacBook Pro (Retina, 15-inch, Early 2013)
I'm not sure of the keyboard's age. I've had it 3 years. It's an Apple aluminum extended keyboard.

Your aluminum keyboard should be compatible with your rMBP regardless of the age of the keyboard. I have two keyboards: One is the older model, the other is the newer model and both work OK with my late 2013 iMac 27". Has your keyboard been subjected to a liquid spill at any time? If not try this: Remove the keyboard from USB and hold it upside down over newspaper. Use the flat of your hand and lightly hit the back side of the keyboard. You should see pieces of dust, skin, and dirt come out of it. Keep doing that until no more comes out. Try the keyboard again to see if it made a difference.

Unfortunately dirt isn't the issue. This seems like a software-only issue since I'm locked out of using the keyboard to type, for example, the Q key. But then holding down the Command and Q key immediately after that and the app quits. So something in some part of the software.

OK, doesn't hurt to clean the keyboard anyway. But try this first: Boot into safe mode (hold down the shift key and reboot). Let me know how typing is when in safe mode. That should eliminate software problems.

Sounds like a usb port fault.

Easy to diagnose get a powered usb hub connect it to your macbook in question then connect the keyboard to the usb hub if its the usb port you should still lose connection with the hub connected just a lot faster but if the keyboard works then your having a usb voltage drop problem and need to get the machine serviced as soon as possible.

i would also recommend looking at another extended keyboard as they can generate false positives as well.