I woke my Black MacBook from sleep, but all I could get was the beachball, nothing would respond. So I figured it needed a reboot,( I had a lot of programs running), so I held the power switch down until it shut off. Then I restarted it. It chimed and went to the white screen, then just stopped. After about a minute this gray folder icon with a question mark started flashing on the white screen. I've never seen that before, but it can't be good. Anybody know what to do next?