Hello. I have a few questions: I was working in the library yesterday. While I worked on a wooden desk, a student studdently dropped a heavy book on the desk. Since then, I feel that there are slight vibrations when I rest my left palm on the machine while typing. Do you think it is caused by the incident? I worry that she might have damaged the hard drive of my MBP by suddently dropping heavy book on the desk where my laptop rested. Please note that somebody else did this to me once before. Yesterday, I had the Zeroshock III 17-inch in between the MBP 17" and the desk. I wonder if the it could reduce damage caused by this kind of incidents. Any idea? This brings me to the question of how motion sensor works. I heard that when the sensor senses motions, it parks the drive head. However, in the case mentioned above, the movement is caused by the desk vibration (an impluse caused by a sudden drop of heavy objects next to the laptop) rather than from moving of the laptop. It might be too late for the sensor to sense the impluse. Anybody has an idea how the sensor works in this case?