In the past, a hard drive "crash" was often associated with the read/write heads on the hard drive physically "crashing" into the platter, thus scratching the platter and making it unusable. I understand that this can still happen every once in a while, but given that most people don't jar their hard drives around alot, this doesn't seem to be very common anymore.

Other things such as a piece of debris flying around inside the drive chamber, circuit failure, or a power surge sounds to me like much more likley causes of a hard drive going bad.

So, my question is, what are the more common causes?