Jongware,
I have been checking the epubs in ADE, Sony Reader for PC, and in the Nook for PC. I don't have a Kindle available, haven't tested it on the iPad yet, and Mobi doesn't have a download (that I can find) for Windows 8.
In ADE and Nook, the break occurs at exactly the same point, even when I change the screen size and therefore change the page count.
In the Sony Reader there is no problem, for which I am grateful but it confuses the issue even further. I had originally thought it was something in the Word doc, but now it appears that you are closer to the root of the problem. I will try to find the controls for the maximum characters or paragraphs to see if that corrects the problem. If it does, I'll be doing my little Snoopy dance.
Thank you for the suggestion.