The Daily WTF, today from CNN:

Oops! Technician's error wipes out data for state fund:

Perhaps you've experienced that sinking feeling when a single keystroke accidentally destroys hours of work. Now imagine wiping out a disk drive containing an account worth $38 billion.

That's what happened to a computer technician reformatting a disk drive at the Alaska Department of Revenue. While doing routine maintenance work, the technician accidentally deleted applicant information for an oil-funded account -- one of Alaska residents' biggest perks -- and mistakenly reformatted the backup drive, as well.

There was still hope, until the department discovered its third line of defense had failed: backup tapes were unreadable.