You know what...

I dont own one, but there is one TI-83 in my math class that has games on it, like mario and stuff...graphics do suck, and the gameplay sucks ass. I say delete them, and re-download it. Or I think there is something with the mode or graphics. Go to Program and just mess around with it, but since only I do that and it isnt really reccomended, I say you should go to your users manual and go to Troubleshooting I guess.