Hi Rajesh,
I just had the same problem and I was looking all over the internet without any luck. My scene is huge, in fact, the vray is dropping me the common error "scene bounding box is too large" but I learn to not to pay attention to it. I've finally found the problem of the UNHANDLED EXCEPTION. As m.o.n.s said, it is a memory problem, so when I knew that when I readed that in some other post, I increased the memory of my pc to 8 gb (Im working on Max 64) but it didnt solve the problem. So after a few trial and error with my scene I found that the problem was a new light that I was using, a native 3dsmax light with native shadow map. I readed in some other forum of vray, that it cant handle correctly the memory that that kind of shadows require so that gave me the clue. The problem wasnt exactly only that light, the problem actually was, that that light was affecting hi geometry object with a vrey complex shader of water. When I turn off the layer of the object and keep the light there wasnt problem, but for me, the final solution was to turn off the light, obviously and use a vray light or use an standard light but with vray shadow maps. Hope it helps you.
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