Macbook pro 15" keyboard freezes only function keys work I am facing a very weird problem with my MacBook Pro 15". I was working in Xcode 4.2 and when I option-click in simulator (to simulate multi tap) my keyboard stops working.  The weird thing is that only the a-z and 0-9 keys are not working...

By the way I am using a bluetooth mouse... and recently updated my system to MacBook Pro EFI firmware update and I am running OS X 10.7.2 Lion.

I had to restart my system to get the keyboard functionality back.

Is this a bug in the OS? How can I get rid of this problem?

Thanks in advance
Finally got it. I was pressing option keys lot of times and pressing it 5 times enables mouse keys (which disables keyboard keys).

To reverse, go to "Settings -> Accessibility -> Mouse and Trackpad" and uncheck "Press the option key five times to turn Mouse keys on of off" or simply uncheck "Enable Mouse Keys."