Bummer...whenever I'm doing something critical, I like to manually save it every couple of minutes and make new copies as I go. In addition to the file name, I like to include the date and the time so I can go back to any point along the way without a lot of hassle.
Typically, a file name looks like this: 9-15-12_filename_836am (date/name/time)
Each new save only requires changing the time it was saved.
It takes a little work to do, but it sure saves a lot frustration.
JB