Ursprünglicher Beitrag von: sween ,
I had the exact same problem and I just fixed it completely and for free. I simply tightened all the screws on the underside of the macbook holding the unibody together and it went away instantly. If you can make it go away by pressing down on the back then perhaps the same fix would work with you? Something must be loose though for just slight lack of pressure to cause this problem I imagine...