An anonymous reader writes "According to this report by IT PRO, scientists working at the University of California have discovered the main reason of hard drive failure. According to researchers, some materials used in hard drives are better at damping spin precession than others. Spin precession of magnetic material effects its neighbors' polarity and this can spread and cause sections of hard drives to spontaneously change polarity and lose data. This is known as a magnetic avalanche. So next time Windows fails to start, you'll know why!"