Interior Scene: Yafray corner question


recently I created my new appartment in Blender to see how I can put my stuff into it. Basically it works good but I have some nasty problem with Yafray.

The problem is that corners are lighted up too much:

What I am doing wrong here (maybe settings)…? Does anybody know? For me it looks like that the corner areas collect too much light in the GI process.

Second example is in attachment.

Thank you very much for your help

  • Tiberius