Keyboard fails to function; trackpad and power button still work.

Hi all,

I own a white 13-in. Macbook purchased in June 2006. Recently it has been giving me problems with typing. Occasionally, my keyboard fails to function. If I wake my computer up from sleep, sometimes it will not work (e.g. I can push any of the keys and nothing happens, apple-option-esc does nothing). However, I can still use the trackpad, and the power button works. I just cannot type using any of the keys on the board. This has happened three times now, and each time I have simply had to reset my computer in order to restore function. I always have a sufficient amount of battery to run the computer when this happens, too. Is there a probable cause for what is happening?

Thanks for your help and suggestions.


All parts on my Mac are original except for a new battery from December 2009.