My macbook is about 3 months old. Whenever I open my macbook, a strange noise comes from the slot where you insert a disk. It sounds like it's loading a disk, and does this about 4 times until it stops. I have pressed the eject button, nothing comes out, and still happens whenever I open it. It's not just when it turns on, it's whenever I open it from it being closed/sleep. I have tried restarting but the problem remains. Help?