Out of 19 chapters in the file I am working on, I found that at the end of the 15th one today, somehow it had become a "continuous" rather than a "next page" section break, as a result of which the chapter heading for Chapter 16 had moved up onto the last page of Chapter 15. I thought ok no big deal, I'll just remove the continuous section break and put back the "next page" section break. It worked fine, but then I found to my dismay that the section break at the end of chapter 14 had now become a continuous section break. So I removed it and replaced it with a next page section break. But by so doing, the section break at the end of chapter 13 had now become a continuous section break. Why is this spreading like a cancer from one chapter to the previous one every time I fix it? And when it happens, it ruins my footers as well, turning the x of y page into chaos and renaming the chapter in the footer to that of a later chapter.