Not possible to paginate in ADE 4.0

Windows 7; Adobe Digital Editions 4.0

I have just installed ADE 4.0, then opened the welcome.epub file.  It just sits there, displaying page 1/9, but neither the Page Down keys, nor moving the slider at the bottom of ADE will go further than page 1.

Only after using Reading | Go to page... it will actually paginate within the document.