I had the same thing happen to me recently, but mine was a big project with verses and a linked TOC and footnotes and represented hours and hours of work, almost all lost (when I reran BD, it loaded up some early version of the book that it got from who knows where.) I resolved never to make another book without saving a copy of the last file first.
If you're inclined to redo your work, you might save the last file first and if the book crashes again, load it from your saved copy and try it again and if it still crashes, strip something out of it to see if you can identify what's causing the crashes.
Are you causing page breaks where BD would automatically put them in anyway? Just a thought.
I feel your pain.
Jim