Weird HDRI renderings

I’ve got a problem with Yafray renderings when I use HDRIs. When “cache” is pressed, I get very strong, saturated colors on my base surface (a marble texture - high spec, ray mirror of 0.05), which is not what I want. Without “chache” the surface just appears very grainy, kind of AO-like except really bad. I once managed to render the image the way I wanted it, but I don’t remember the settings now. How do I fix this?

Good:
http://img188.imageshack.us/img188/7144/goodrender7ck.th.jpg

Bad:
http://img343.imageshack.us/img343/6827/badrender4og.th.png
Thanks in advance.

While I don’t really know whats causing this, try turning down ray mirror to an absolute minimum (or completely off) and see what happends.

Yup, I’ve tried that and it doesn’t work. I get pretty much the same result.

Try the texture filter parameter, set it to some value higher than 1, this will enable ‘prefiltering’ of the hdri.