Crash: Saving and loading a book with some pages crashes

[milen]

Saving and loading a book with more than 2-3 pages crashes. The crash happens in different ways depending on the saved book. Sometimes the bug occurs immediately after loading the book, sometimes while going through the pages of the book, sometimes when changing the pages' content. Sometimes the application only throws an exception but usually it crashes because after the appeared exception is closed another one appears and so on. Here is an example of crashing:

1. Create a new book.
2. Insert a text frame in it and include a text in the frame.
3. Add a new page by clicking on the arrow for the next page.
4. Change the background of the new created second page.
5. Add a new page by clicking on the arrow for the next page.
6. Save the book.
7. Open the new created book.
8. Try to go through the pages and notice the application crashes.