A few years ago, a student in the college library where I worked was complaining because she'd e-mailed herself a paper from home, opened the file and made changes when she got to the library, and saved the paper, but when she went back into it, it had reverted to the original draft.
Concerned, I came over to her computer and watched her go through the steps to see what the problem was. Sure enough, she opened the e-mail attachment, made the changes, saved the document to the desktop, closed it...and went back into her e-mail to re-open the document. The original document. The one that she'd attached to the e-mail in the first place.
I don't know how many times she went around in circles doing that. I tried three different ways to politely explain why the e-mail attachment wasn't going to magically change just because she'd saved a new version on the computer, but to this day I'm not sure she figured it out.