TT-B Won't Save My Return: Unable to Proceed

I am using Turbo Tax for Business 2017...the CD version. I'm on Windows10 (up-to-date). I have used TT for my business for many years.

 

I am unable to save my file. When I select SAVE (or SAVE-AS) and then accept the default name that TT-B suggests, I get an error message saying "File not found. Check the file name and try again." Even if I change the filename to something simple ("TaxReturn"), I get the same error. TT-B seems to be looking for a file rather than trying to create a new one.

 

My program is up-to-date. I have tried saving to various locations with the same results. I have tried different file names. I have rebooted several times. I've tried running with no other programs running.

 

I'm dead-in-the-water!

Thanks for assistance.

-bs