have you tried "divide and conquer"? Export the book in two halves, then any half that fails divide and export in halves. Reapeat until you isolate the problem.
If both ahlves work, it's a system resources isssu and you have to live with combining the halves in Acrobat.
The problem seems to be scattered throughout. The most consistant thing I've found to work is single left-hand pages, or pages without a right-hand master. This is why my theory stands that it has something to do with the overflow on the right-hand page.
Make sure that your book isn't selected in the Finder window (Mac) in the background. Whenever I exported my book, it would launch so I could review it. Even if I closed the book (PDF), if it was still selected, or highlighted, it would cause issues.
Just a thought.