Hmm. If it's anything like the car player software, then I would suspect that one particular track is giving it grief. Perhaps something with a filename containing a strange character, or maybe a file with messed-up tags or header data. For example, a V2 "comment" tag that's greater than 256 characters long or something.

Go through the newly-added files with a fine-toothed comb and see if you can see anything like that.