Hard disks crash for various reasons. One of the more predictable offenders is unstable power supply. When there is a sudden power outage or sudden power surge, hard disks can take quite a pounding. Aside from physically damaging the disk, logical errors to the disk’s file system can be traced to this reason. Logical errors for such happen when the disk suddenly loses power while it is writing critical information to the disk. Such errors can make the data on the disk unreadable unless the file system is corrected. Viruses and malicious code can also be a cause for a crash, as well as the ill handling of a disk – sudden shock, dropping, or magnetizing can seriously damage your hard disk.