At first I thought the jagged sharp shadows were caused by two objects overlapping, wrong material or environment map.
Now I know so far that this happens all the time.
I'm importing obj and fbx models from 3Ds Max. Quads or Polys.
Watch these renders to see what I'm talking about. Is there a way to fix this?
(http://img716.imageshack.us/img716/5585/arqrender1textured93.jpg)
(http://img17.imageshack.us/img17/9181/fotocreativo85.jpg)
You will need to use a higher shadow quality. You may also want to increase the number of samples used. Both can be adjusted in the quality tab in the rendering dialog. Finally, you may want to increase the tessellation quality of the model exported from 3ds max.