I've only noticed those corner splotches in scenes where I loaded the walls independent of each other. I noticed that increasing the thickness of the walls, or having them intersect each other ever so slightly also reduces the splotches. Lowering the shading rate to .2 or below also does away with them. I haven't experimented with much of what has been posted here, but I intend to see what Poser 9 on a 32 bit system will produce, seeing as I can only render in 2 separate processes...

If I had a nickle for ever time a woman told me to get lost, I could buy Manhattan.