Since attaching an external USB keyboard my laptop keyboard had been useless – press certain keys and the wrong characters came out. Wasn’t a huge problem until recently when I wanted to take the laptop somewhere without lugging along the external keyboard. We needed to access data from a password protected Sandisk and ended up locking the thing because of the keyboard issue.
On a day off so searched the net to find someone on Yahoo with the same problem. And the solution was to turn off the NUMLOCK key on the USB keyboard. Problem solved!