I discovered this morning that there is a recommended update to Adobe Digital Editions 4.0.2 which fixes some issues in display of EPUB3.
This is copied from the Release Notes page:
Changes in ADE 4.0.2
If you are using the earlier version of Adobe Digital Editions, we recommend that you update to 4.0.2
Here is a link to the download page:
Thank you Steve.
Thanks a bunch Steve!