I think there’s something amiss with that “single song” that’s causing the problem. Most likely an ID3 tag issue. Try removing this file from the player (or card) and see if the problems doesn’t correct itself. If it does, then you’ve isolated the problem and know you have to edit the tag.
You might also try removing the card, powering up the player and see if it responds correctly, then turning it off and re-inserting the card. That can sometimes work as well.