Data Backup Blog » Top 10 Data Recovery Bloopers:

My personal favourites:

5) An Almost Perfect Plan
The company purchased and configured a high-end, expensive, and full-featured library for the company's system backups. Unfortunately, the backup library was placed right beside the primary system. When the primary system got Fried, so too did the backup library.

and

9) Hit Restore and All Will Be Well
After September's WTC attacks, the company's IT staff went across town to their backup system. They invoked Restore, and proceed to overwrite from the destroyed main system. Of course, all previous backups were lost.