On screen lock screen, the keyboard does not work, switching to the switch-user screen the keyboard works again

Question

Mac OS-X 10.7.5, Mac Air.
This began about 5 to 7 days ago.
Steps to reproduce:
Step 1:
Close the lid, or the system 'powers down', or goes to the screen saver mode.
Step 2:
Open the lid, press the power button, or what ever to wake up the Mac Air
The "Enter your password" screen is presented.
They keyboard is not responsive, I cannot type anything.
The touch pad works, I can power on/off the machine.
They keyboard is not functional.
Result: I cannot log in again.
Expected behavior: The keyboard should be working I should be able to unlock the screen.
Workarounds:
Then click on my name, or any other user of the machine and it works fine.
I can now unlock the screen and return to where I was.
Expected behavior:
I should not have to go to the "Switch User Screen" to log back in.

Answer 1

More detail:  Some keys on the keyboard do work, ie: caps lock toggles the led, and the function keys across the top seem to work {that is I can adjust brightness, and so forth}
the letter and numbers, and perhap others do not work.