Ok, I don't know what's happened, but it seems to be working now.  However, I have the same background image problem that is described in this thread:

 

 

i.e.  I have EditorBodyStyle="background-image: none;" set - the background is not displayed in Normal and Preview modes, but it is in HTML view.  When I click on Preview and back to HTML, the background is not displayed.

 

Has this bug been fixed?