Again, probably a stray mouse double-click.
Your documents show white space or not depending on your Word settings. This is not set in any document. If the setting is changed in one document, it applies to all documents

I read the article, and I'll try the mouse click between pages when it happens again. Not going to create the situation because I may end up with another fight to get it back to the way I want. (The link at the bottom of the article to a further explanation of white space leads to an inactive page) And it's definitely not a mouse click thing. It happens when I open a word document attached to an email.