Quote - Removing the displacment maps (the object has 10 materials and about 5 had the maps) fixed it. 

So the next step is to restore the maos but use less subdivision. How many levels of subdivision were younusing? Remember that each levek quadruples the number of polygons. Very likely you were hitting your memory limit. Lowering the number of subdivisions might solve your problem. That or buying more RAM :)

Paolo

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