Ever get "required HTML form missing js.form.htm" when starting a map viewer? If so, you were probably starting the map viewer from a bookmark, favorite, or email link. Since the map viewers are based on HTML frames, you can not simply "bookmark" the map viewer after it has loaded. The only way around this error is to modify your bookmark (by viewing its properties) once it has been created as the below example:
The URL after the viewer starts and what is bookmarked: