windows 7 - Keyboard stopped functioning for no apparent reason

I was just typing in Firefox when my keyboard stopped working. I couldn't type in any program. After a reboot, however, my keyboard works fine.

Why would my keyboard spontaneously stop functioning? How could I determine the cause?

I do not have a wireless keyboard. I'm using only the embedded keyboard on my laptop.

Possible Windows 7 x64 issue? Or just a weird anomaly?

Note: If at all possible, I do not want to spend any money on taking it to a repair shop. It'd much rather have it fixed myself.

EDIT - 7/7/11: The function keys seem to be working. I can still toggle the backlight on my monitor with Fn + F8.

EDIT - 7/13/11: I have to use my wireless keyboard whenever my laptop keyboard stops functioning.