How old is the laptop? If you primarily use the laptop’s built-in keyboard (as you would on your lap, no doubt) then it will wear out. It’s not an expensive item to replace. If it’s still under warranty, talk to Dell about a replacement keyboard. If it’s old / out of warranty, then find a repair shop (any repair shop that you trust) in your area, and they should be able to change out the keyboard while you wait. It should take no more than 10–15 minutes if they have the thing in stock. And it should not be expensive, either. (With my Dell I first noticed that the center keys: I-U-J-N-M were flaky and unresponsive, and the mouse cursor would drift on the screen even when there was no mouse attached and no one at the keyboard. The repair guy that I have used before says this is a common indication of excessive wear.)