There is a big problem with laptops and people putting them to sleep (hibernation), then packing them up in a NB case, slinging it over their shoulder and going out somewhere.
When systems are in hibernation the hard drive does not park! So you can imagine the movement while you are walking. It can be quite damaging to the platters.
Probably 50% of the notebooks that show up at the Service counter at work are transported in this state. Always shut your laptop system down before you move it around.