update
funny thing.... when I render with Mental Ray not only I fix the problem, but I even get a smoother grid (which I would prefer).
But then again, this really isn't a solution, because mental ray takes longer to render and for some reason it won't do a batch render from the command prompt. So I still want to find the real solution.
There can not be Good without Evil, so then it must be good to be Evil sometimes.
:tup: