Some of the letter keys were typing numbers. My MBP went to sleep after I'd unplugged the keyboard, and I found I couldn't log in to wake it up, because I didn't know how to disable this Num Lock feature on my MBP.
I didn't realize it was possible to get into that Num Lock mode on MacBooks since the 2009 models. and this MBP doesn't even have the numbers on the keys. I also just discovered this: if I turn on Mouse Keys while the aluminum Apple board is plugged into my MacBook Pro, it forces the laptop's keyboard to act as if I'd enabled Num Lock.
