Okay last night i was working on my powerbook with imovie and idvd and noticed it was going a little slow. I left it up and running plugged in like i do once and awhile. When I woke up his morning I heard the hard drive really working hard and I could'nt get the display to come up ( i had the display turned of), and I noticed that the hard drive has a humming noise to it. I then held the start button down to force it down, and then it wouldnt get past the apple. I got it to start once and it froze up. Now it wont start again. Does anyone know whats wrong?