Matt,

I'll tell you what I can.  Your questions are in bold italics:

Where is your ProSeries installation located?   I'm using a Microsoft Surface 3 Laptop with Windows 10.  ProSeries is on my C drive in BasWin20.

Can you provide the full path here?   C:\BasWin20\32bit\protax20.exe

Do you have write access to the entire installation folder?   I'm not sure I know how to answer that.  I don't have any reason to believe I don't, but ???  I guess I have whatever access customers normally have.

Have you seen this issue happen often? Or is it the first time this season?  Last year, when it was happening in the business returns, it was several times, but didn't happen every time.  This year, this was the first instance, discovered this morning.  Once was enough, so when it happened this morning, I asked for help.  Life (and tax season) is too short for this kind of worry!  So, this year, too, it doesn't happen every time - to test it, I put in some dummy figures, and closed the program after 2 minutes (when auto-save should occur) through Task Manager and when I started again, it did offer a recovery file.   Then I closed it again before 2 minutes, and upon starting again, it offered me a recovery file.  Apparently, I can't reproduce it either. 

I will make every effort to train my brain to save every 5 minutes or so and whenever I step away.  I'm glad you agree that I shouldn't have to do this, and I appreciate you trying to find out what's wrong.

Thank you.