When I try to save a file, I am told my file is a "read only" copy
I use Illustrator version 20.0.0 (2015.3)
I have not experienced this problem until very recently.
After I have saved a file, when I make changes to it that I want to save, I am told I cannot, as it is a read-only copy.
I have already checked the properties of my file, and it is NOT "read-only."