Hi folks,
what does "stabilze ray detail in motion" do? 
I had some little black artefacts from raytraced soft shadows and a little trawling around found this parameter and turned it on - cleans up them up nicely.
Don't know what this param is for though, or why it's off by default? 
ray detail in motion - off
[attachimg=1]
ray detail in motion - on
[attachimg=2]