I tested it with my ATI card on windows vista ultimate, and It breaks as soon as I have more than 1 sample. I can set blur to any value I want, and it works, but if I do more than 1 sample the shadows don’t work. The edges of the light appear, and the faces effected by the light look like TV static unless the entire face is covered in shadow, and no blur is applied. I would take a screenshot, but I’m using a mac keyboard and there is no print screen button.
Edit: Figured out how to take a screenshot with a mac keyboard. Here’s a comparison of 1 sample vs multiple samples. Sorry for the low quality, the only image editing program on my windows partition is paint.
It looks the same in the BGE.