Anyone? What settings should I correct?

Hello,
I'm rendering interior scene and I'm having some dark spots in darker areas. First I had many of them, but then increased hsph subdivis and samples to 64/50 in IM. I'm having much better result, but I want a better one, there is still dark spots on the wood on the right side (mulions). What settings should I increase? Here is screenshots, with first rendering and second.