I asked on another post what this relatively LOUD noise is when I pick up my low-end 2011 13" Macbook Pro, slightly bump the right side, and when it leans over on my lap. I've been told that it's most likely my drive heads parking? Can somebody explain this to me? Not sure what that means. This is not causing me any problems, but I am concerned because my 2010 Macbook Pro NEVER did this, which I was much LESS careful about making sudden jerks or movements than my brand new 2011. I am a bit concerned about the sensitivity. Anybody else hear this? Happening in 15 and 17" too? By the way, I'm on my 2nd 2011 MBP and the 1st one did this too.