i had a weird problem yesterday -
i've opened a maya scene, change some of the render settings and pressed the Batch Render.
it's an animated scene of about 500 frames, and in the Script Editor, it showed me right away that "mental ray finished rendering"..
of course it didn't really render anything.
but after i saved the scene and hit the Batch Render again, it rendered correctly..
is this the way things work? or is it just a bug?