You either have a mechanical issue with that one Z axis screw, so it's either tight on the thread and nut or sometimes the nut is so loose it tries to jam on the thread. If you have heaps more up and down play on that thread than the other Z axis it could indicate this. If it is tight you might have to pull that thread and nut out and see if it's just tight in one spot on the thread or all the way.
Other thing is the Vref for the Z motors should be checked to make sure you are giving the motors enough power.
and maybe you have an issue with either the driver or that motor. You could swap the driver from say X axis to Z axis and see if the issue moves with it.