I'll have a bunch of self ripped audio books, mp3's that I've marked as 'audiobooks' in options. Everything has been fine for a while but suddenly if I add an audio book to the list, I'll get a message saying that iTunes can't transfer because they are in the wrong format. As soon as I add an audiobook, the bar at the bottom of iTunes suddenly shows empty for audio books. It will copy the new one but remove the old ones. If I shut iTunes and reopen it and sync again it will transfer everything no problem. However as there are hundreds of files, this is getting a bit annoying and has only recently started happening. Also I'm not sure if this is linked to this or not but also 4 apps wouldn't transfer saying the computer is not authorised but it is. I signed out and signed in but could not get them to transfer, eventually I discovered I could just redownload them from the cloud and then it was all fine. But it's this sudden business of my audiobooks being constantly deleted then being transferred from scratch that I'd like to solve. Any clues on what might be causing this. This has only recently started happening after having no problems for a couple of years. I also did a restore of the iPod but that didn't help. Any clues?