Unable to play a complete track in iPod nano
These are few things, which may be helped (they helped for me sometimes, because this problem is too sudden).


Reset your iPod (keep your music safe before this operation, of course);
Try deleting all staff off the iPod and re-syncing them;
Try both variants which are above together;
Maybe try to convert your track or find another same variant.


Also see this useful Apple's info.

Good luck and happy holidays!