Comment Times spun up was a factor too (Score 2) 164
Stopping and starting a drive is also a moment where you can break/wear down a drive. This can be explained by the fact that heads rest on platters (unless in parked position) when the platters are not spinning at the right speed. Also, because a drive that is being spun down will cool down and warm up again when being spun up. These temperature fluctuations will be of influence on the drive reliability. The most plausible explanation I can come up with is that temperature shifts will make parts inside the drive align differently, possibly permanently changing alignment enough for head-misalignment to occur.