When I render an emitter with Particle Repopulation in the Viewport with turned on Motion Blur C4D crashes.
It seems to happen with every Particle Input Type.
When I render in Picture Viewer everything works all right!
See example scene attached 
Cheers,
Raphael
MB_Emitter_Repop_01.zip (618 KB)
I kinda disagree. There are A LOT of other things not working right in this setup, not just motion blur crashing in the viewport. 
*If I render the scene you sent as it is, and then disable motion blur, it is obvious that the particles are 1) not blurred when they should be and 2) rendered in the wrong location when motion blur is on. So there is something messed up with the Velocity channel, too.
*I get a crash with Motion Blur on but Repopulation off even when rendering to the Picture Viewer. 100% reproducible crash on my system.
So I am going to log several bugs related to your example:
*Crash when rendering to the view with Repopulation and motion blur on
*Crash when rendering to Picture Viewer with Repopulation off and motion blur on
*Incorrect placement of the particles when rendering with Motion Blur on
*No Motion Blur effect in either Jittered or Not-Jittered mode regardless of number of samples
Thanks for the report!
Thanks a lot for testing and even extending the bug-list.
As I´m new to Krakatoa please forgive my simple approach to things right now
I´m sure as I´m geathering more knowledge I will write more accurate bug-reports!
Edit:
This was a rebuilt from a more complex scene with ThinkingParticles.
With TP I only had the reported problem. MB worked fine in the Picture Viewer.
I guess that the other points are C4D Std. Emitter related.
p.s. I haven´t mentioned that particles with turned on motion blur would not render in the viewport because it was mentioned in another thread!
Cheers,
Raphael
Keep in mind that motion blur rendering in the editor/viewport isnt supported by cinema 4d itself.