Hi I have an almost 3 year old Macbook, i bought it the week macbooks were out. Yesterday it unexpectedly made a noise like something metallic moved inside it! The noise is like coins falling down in a laundry machine. It scared me a lot. It happened first when I was holding it up in the air while moving, So I really thought something moved inside. Then I thought it was the chain on my wrist making the noise. But it repeated 3-4 times yesterday and today it did it again while sitting on top of the table, I was not even touching it. Does anyone knows this sound and why it happens?