Attached Link: http://www.renderosity.com/messages.ez?ForumID=12356&Form.ShowMessage=1690930

As for how they figured out what the problem was...it's not quite as random as it seems. They know what they "fixed," so they have a pretty good idea what they broke. :-) You know how Poser 5 has a habit of leaving shadow temp files in random places without deleting them? Well, SR4 was supposed to fix this. I have a feeling that this is what broke shadows in SR4. The link is to the thread where a tech guy from CL tries to explain what causes the problem.