IBA lost content/crashes regularly

iBooks Author V2.3 (780)/iBooks V10.1,
MacBook Pro OS X Gold Load V10.9.5 (13F1096),
2.6GHz Intel i7 processor, 16GB Memory, 1600 MHzDDR3,
Storage 366 GB Free of 499 GB
iBooks Author file size 745 MB

Composing the first of six books in iBooks Author: Numerous chapters and sections (created from a blank IBA

template) containing text, static graphics (.png & .jpg), many popover widgets with a .jpg graphic laid on

top, popovers contain text and hyperlinks but no other media, approx. 800 landscape pages, one .jpg graphic

on each of the chapter and section master pages. Two sections have "crashed" so far, meaning that the text

and graphics suddenly disappear. The section master page art remains, but all text and graphics in the

section disappear. Linked (but empty) text boxes are still intact. One section was 445 landscape pages, one

was 143 landscape pages-had to rebuild both each time. Total file size is 745 MB. Might anyone know why this

is happening? I have five more books to compose...

Another persistent issue is that IBA crashes regularly. I've learned to save each page, back it up to

external disk every 30 minutes, and restart the MacBook regularly. Sending reports to Apple, and will try to

capture the error stack next time it happens.