Keyboard 'sticking'

I had this problem a year ago and I seem to remember it was a simple solution but for the life of me can't remember how. My mother is now having the same problem and I'm trying to help her and wondering if anyone here can help. The letter 'a' on the keyboard is sticking, whenever you type an 'a' it types several a's. You can backspace and remove the extra a's but it's a nuisance to try to get anything typed. I told her she could try and detach the keyboard and then reload the driver, but it seems there was a simpler solution, something about hitting ctrl+something else on the keyboard that "reprogrammed" the keyboard. Any suggestions?