Currently Being ModeratedNov 7, 2012 2:54 PM (in response to prkos)
We had the same problem. We got the best results from these changes:
1. Optimize your media. Compress your audio farther than Apple recommends.
2. If you are specifying any audio files in the XHTML, remove them. Code like this was especially problematic for us:
<audio id="myid" src="audio/myaudio.m4a" ibooks:pause-readaloud="true" />