Hi all, I have been reading posts here on MacRumors for ages and I decided to create an account. I have a slight problem and I think this is the place where I can get my answer. I'm not sure if my macbook has a broken HD or OS. when I boot up, the screen goes white and i eventually get the blinking grey folder at the center of my screen. What does this mean? Im running OS 10.5.8, 13" macbook white with clicker, 2GHz intel core duo, 1 Gb 667 MHz DDR2 SDRAM. I also have another working macbook same specs excepts it runs OS 10.6.3. I back up my files using an ExHDD. What possible solutions can I do?