When I use my MacBook and have a bit of movement, I hear a bit of creaking particularly on the right side of the Mac but it can be on both sides. This also occurs when I open or close the Mac. I took it to Apple about 3 days ago and they said something inside was a bit loose and tightened it. A day later, voila, the problem was back. Though I'm not sure if it is an internal problem or not, could this just be the pentelope screws on the bottom loosening?