The iphone and ipod touch can both run into problems playing audio books. When this problem happens the ipod or music application quits unexpectedly when you are playing an audio book. This seems to happen if you have more than 20 audio books synced to your ipod touch or iphone.

One obvious solution is to sync fewer audio books. But if you really want 20 or more, the work-around is to put them into a playlist and then sync the playlist. You'll then be able to play audio books without getting any errors.