Ok, so if I have not said it 1000 times to anyone who would listen. SharePoint is that product that I love to hate. In my latest waste of 10 hours, I have been trying to use SharePoint designers site backup feature. I follow all the steps and as it would start going it would error stating that the "User cannot be found." Well, flippin' great! What does that mean?
So I proceeded to spend the next few hours trying various combinations of making me an owner (which I was), making 'Everyone' owners, and any other crazy hair I could imagine. Nothing worked. Of course Google did little good. Once again critical thinking saved the day. In one article or comment, someone said something that led me to believe that under the covers SPD was using the export feature. So I changed the nature of my googling and found one lone article on the matter.
So thank you Michael Van Cleave!!! Your article worked great for me. It turned out that the author of the site was an old intern and they were no longer here. I followed the guidance of updating the site author to me and I am now able to back up that particular site.
I hope this helps with others facing the same issue.