Intersecting low poly geometry? Update video drivers? Time to use a sky light, switch the material color to white and render a diffuse/Fake AO map? Dunno really, haven't run into that before, weird...
I don't have Max near me, but my workflow for setting up an MR render is as follows; Set your renderer to Mental ray (duh) Apply an ambient occlusion pass to your diffuse of the material Samples anything from 100-300, spread around 2.5 Right click on your lowpoly, properties -> object ID should be a positive number, we''ll…