Yes, fls13, if the shadows start to get fringed that means you may have gone too low with the setting - it is a delicate balance depending on how the object was made, and whether edges are "welded" or not. On contoured edges, you can safely weld them (using the grouping tool) to get rid of the problem. You can also try selecting the troublesome object and turning OFF the ray tracing for that object. This is a problem that most Ray Trace render engines have and it is due to the light rays trying to illuminate or shadow through the "cracks" in the object. The angle of the light hitting the object also has an effect on this problem, and sometimes just moving the light a bit will cure it.