A teacher of mine once asked me if i could take a look at his external HDD because all the data was suddenly gone. Important holiday pictures and stuff...

Turned out he accidentally created a Windows 7 "library" based on the root directory of the drive. Next logical step to get rid of it: delete the whole content because "i don't need the data twice".

Explained the concept of directory links and restored the files...

His wife later asked him about the reason for the data loss. He didn't have the balls to tell her that he deleted them himself even though he knew it at that point =D