Our less-than-savvy Financial Director took it upon himself to restore from tape the bought ledger files to a live system after a slight mishap. Unfortunately, the bought ledger files all started with a 'b' and he managed to restore them to the root of the -nix system instead of the right place, so he mv'd b* to the right location.

All was well until a scheduled maintenance restart a few weeks later and we (eventually) discovered that /boot and /bin were AWOL.

Edit: He had access to the root account to maintain the accounts app (not my call)

I have nightmares about such things.