I was using the most recent beta, 2181 since it came out. Today, in the middle of working, the power failed and the computer shut off. When I rebooted and went back to my file, it was zero bytes -- empty.
Fortunately, it was a web page and had already been deployed to a server so I pulled down a copy. But still!
I see the most recent dev version has a new way of saving, so now I am going to use that.