I have. When I edited a photo yesterday, I thought I lost the original, so i took a backup from my other HDD and over wrote the file on my iMac's Hard Drive. When I did that, the file went to 0KBs and basically got corrupt. Then everytime I opened iPhoto I got the same msg b/c the file in my library was corrupt. Basically I had to delete the file and replace it with a file from my backup.
Also, it turns out, that when you edit a file, it creates a backup in a directory called "Originals". This I did not know, so I ruined my edited photo for nothing. Live and learn.
Thanks,
Ray