Effects won't play on this computer???

I could swear I used to be able to use the Comet, Confetti, and Flame build in effects in KeyNote on my iBook - now all of the sudden it lists these at the bottom of my effects list and says they can't be played on this computer.

Anyone have a solution? I saw another post were someone created a "new user" and that worked for a bit. What's the final answer???