After a failed attempt at install XP( my disk was to scratched), I repartitioned my drive as one. Everything seemed to be working fine. NOW, when I boot up my macbook, it never hits the apple logo and gives me a black screen saying there is no disk to boot (something like that). In order to boot up, I have to hold the option key down and select macintosh( it is the Only option). What's going on here!?!??!