Keyboard problems with Nancy Drew PC game?

Okay, so I am playing Nancy Drew and the Haunted Carousel. I found the in-game keyboard for the Barnacle Blast game, and now the game is working. However, when I use my computer's keyboard to control the paddle, the paddle makes weird, jerky movements. Like, for example, when I take my hand off the keyboard the paddle is still moving. Not only that, but it takes a while for the game to register that I'm pressing the arrow key. This never happened on my old computer while playing this game, so I know that this isn't supposed to happen. As you can imagine, this makes it incredibly hard to win the game. Does anyone know a way that I can make the game in sync with my keyboard? Any help would be greatly appreciated, thanks.