I used my laptop earlier this morning, and closed the case so i could transport it to school. I arrived at school and when I pressed the power button, the laptop screen and the green camera light both flashed, but after a few seconds I heard the hard drive click off. When it is connected to a power source, the same happens, except the hard drive does not click off until I hold the power button for 5 seconds to force a manual shut-down. I opened the case and made sure all the cables were connected properly, and I found some white powder on the RAM cards (I found some articles here that say that this is normal and some sort of lubricant or something) but I cleaned it off using rubbing alcohol and I made sure that the cards were pushed all the way in. I did nothing at all with the computer aside from closing the case and packing it in my bag, I did not drop it etc. The computer is a four year old Macbook running 10.5, I have not experienced any problems leading up to this that seem to be related. I've only had a problem with the MagSafe adapter (I recently purchased a new one and it has not given me any problems.) Also the screen was cracked about a year ago. Thanks!