I was once finishing a conference talk on the night before the conference. And the moment after I wrote the last sentence, my hard drive crashed. Of course, I had to rewrite the whole thing in two hours, and it predictably bombed. The presentation was so bad that people stared. It was beyond embarrassing.
Since then, I always write directly into Dropbox and then save to the hard drive and to the external hard drive.
What do you, folks, do to avoid losing your stuff?