I see two issues here - first, light leaks at 90 degree corners on geometry and secondly black smudgy splotches. I found a workaround for light leaks - see post here http://forum.runtimedna.com/showthread.php?74474-Backlighting-in-Poser at RDNA. That looks like Jack Tomalin's Classic Deco set, so if you can't alter the geometry I'd suggest trying a couple of high-res square primitives placed behind that area and facing out - haven't tried this myself but it may be worth a shot.

Black splotches - if you increase Irradiance Caching in the render settings to 100 it should (if I remember right!) dispense with the IDL pre-calc pass (ie. no pass with red dots). Firefly will include IDL in the main render pass using brute-force computation which is the most accurate method (ie. fewest possible artefacts) but is also slower - a lot slower. Whether this is a viable option depends on the speed of your machine, the complexity of the scene and your patience!

Finally if you're using an emitter in the scene, how big is it in relation to other objects? Smaller emitters produce more splotches than large ones if I remember correctly.

----------------------------------------

Not approved by Scarfolk Council. For more information please reread. Or visit my local shop.