Are you sure it is the Fifth Icon and not the Fourth. The Fifth Icon toogles on/off Shadows and the Fourth toogles on Depth Cueing. It sounds like you are using Depth Cueing which works best if you render a scene first without Depth Cueing; apply a Gausian Blur or other smoothing in a paint program; use this new image as a background with Depth Cueing on. There are a couple tutorials for depth cueing here in the tutorial section. I hope this helps, sama