For the moment I have replaced

 

    Editor1.SaveFile(mydocument); 

 

with

 

    SaveHtml(mydocument);

 

And

 

     public void SaveHtml(String FilePath)
     {
           StreamWriter sw = new StreamWriter(Server.MapPath(FilePath));
           sw.Write(Editor1.Text);
           sw.Close();
     }

Which seems to do the trick!  Thought I'd include it in case it's helpful.

 

Cheers,

 

-Colin