There’s’ something about (or in) one or more of the files you are attempting to copy to the player that it doesn’t like. Corrupted file, bad or wrong format ID3 tag, humongous album art image embedded in tag, etc.
That’s what causes database refresh freeze-ups. Also realize that the player is trying to digest twice (more or less) the amount of data when refreshing both the player’s internal memory and any content on a memory card. Sometimes it can seem like it’s frozen when you don’t see the progress bar moving, but it’s actually working.
