FWIW, I also experienced this when unmounting a USB stick using nautilus. Because I pulled out the USB stick too quickly, I ended up with a corrupted filesystem. :-/
Cheers, Richard -- __ _ |_) /| Richard Atterer | GnuPG key: 888354F7 | \/¯| http://atterer.net | 08A9 7B7D 3D13 3EF2 3D25 D157 79E6 F6DC 8883 54F7 ¯ '` ¯