Last night about 4:30pm last night there was a problem with a student's C++ code so I went to help her debug it. She had written all the code but the compiler was not compiling it, thinking it was an empty file. So I went along, closed down her existing windows and opened a few of my own to poke about. Net result - reverting from her finished code to an empty skeleton file.
Convinced I'd somehow lost a day's work for her, she got very stressed. I ummed and ammed, similarly convinced that I'd not done a very stupid thing and that in fact she had saved her work in the wrong folder, not lost all her work. I even (for I am a Linux noob it has to be said) got one of my colleagues in, looked around, found nothing and started talking extension. He thought it best we assume responsiblity given the doubt (and the student was very earnest in thinking she was screwed as she had 2 more assignments due in, a train ride home to catch, a project etc.)
About 15 mins later she came back to the office saying she'd actually saved her code in the wrong directory and was very apologetic. She even came back this morning to drop off a box of chocs for yours truly.
So the story had a happy ending.