I downloaded 3 audiobooks from Audible. The first one downloaded fine, but after that two stopped midway because there wasn't enough space on my computer. But in all my computer's brilliance, instead of just cancelling the download, it promised to download "as much as possible". Well, after I freed up the disk space, I finished the downloads and put them on my iPod Nano (7, I think).
I checked to see if they worked. The one I successfully downloaded on the first attempt works fine in both iTunes and on my iPod. As for the other two, they work fine on iTunes-- I checked the critical parts, towards the end of the audiobook, where presumably the download failed. It's fine. But on my iPod? Just as I might've suspected, when I try to play the last few chapters, they crash. They don't play, or if they do it's a meaningless "freeze" sound, for lack of a better way of describing it.
I deleted the files from my iPod and my computer and downloaded them again. Same thing happened. The fact that they work fine on iTunes and not on my iPod tells me that this is not a case of corrupt files from Audible. And the fact that it's only the last chapters that "freeze" tells me this is related to the download being interrupted. But why it works fine on my computer and not on my iPod, I couldn't tell you.
I also reset my iPod to the factory settings, erasing all the files and resyncing with iTunes. That didn't work.
A computer programmer I know suggested that there might be metadata that made it to my iPod that's messing everything up. We did a little troubleshooting but got nowhere-- we tried without success to find the "invisible" files on my iPod.
And I know there's the Audible app for iPhone, but I prefer to keep my audiobooks on my iPod, as it's more compact and easier if I'm listening while exercising.