Word 2007 fully updated running on Windows 10 Home.

After typing a few paragraphs in an existing document (docx) Word suddenly moved the cursor to the first line on the first page. At the time I was working on page 39. I went back to where I was typing and the new paragraphs were gone. They had not been saved.

This has happened a couple of times since yesterday and the Document Recovery pane did not appear each time it happened. Word does not completely crash, i.e., shut down. I have been working on this document for over a year off and on and never had a problem until yesterday when this behavior started.

On one occasion I saved my work after typing a paragraph and the cursor jumped to the first page again and the paragraph was not saved.

I'm at a loss to know why this is suddenly happening and what to do about it.