Windows 10. GTX 960 TI
Short description of error
I've now rendered 3 different animations with those same stars and 2 of them had frames in random places where the motion blur creates bad errors. Frames with and without the problem:
Exact steps for others to reproduce the error
The only way I know to do this is to create a particle simulation that emits mesh objects. If you have emission shader on the particles, it makes it easier to spot the frames where the problem is. Now activate motion blur and render the animation. Sometimes you have this error because of unknown reasons. In my simulation, it was the frame 64, but cannot anymore be able to have the problem in the same frame.