ok.. on your MayaSoftware renderglobals. Under Memory and Performance Options. what are the settings for the RayTracing there ?? Recursion Depth, Leaf Primitives, Subdivision Power.

you might have got one set off.. I have 2, 200, .250 for thoughs settings..

we could start with that.

a nother option is to post your file so I or someone could try to figer it out.