I have this macbook, a real nightmare. It was working fine until i wanted to sell it (of course). I knew the combo drive was slightly defective due to the fact i couldnt boot from it. But, all of a sudden, it makes a continuous quick ejecting noise when you power it on. The screen turns on, but stays black. No startup chime, nothing. Just that sound. I have since changed out the drive (no easy task) and still the same thing WTF? any ideas?