Edit: SOLVED - constant bitrate fixes it. This person was having a similar issue with timed text http://terrillthompson.com/blog/624

I like to listen to audiobooks during my commute and the standard radio does this just fine most of the time by switching the Source to USB and just playing the files there.

My question is about the resume feature. For most books, when I turn the car off and turn it back on again, the book resumes exactly where it left off. (Maybe a couple of seconds before, which is perfect so you know you haven't missed anything.)

But for some books playback seems to rewind for several minutes so I am re-listening to material I have already listened to. Attempts to fast-forward just rewind to an earlier position on the audio file.

Is there some kind of format I should be paying attention to with my MP3 files to prevent this? Do I need to adjust the bitrate mode or something? (I see options for variable and constant.)

Anyone else have this issue?