The file you sent worked great to get the File Manager working.
I do still get the same message as the "Error pic" every time I use DA on this project, but it still works fine.
I did create a blank page and tried WebAssist -> Forms -> HTML Editor -> Site Settings
just to test but it gives the same error message and closes the window.
As far as this project I am all sorted out and work is moving forward. :)
Just wanted to give feedback for any help it might be in future development.