Hi
I've followed the advice in the splotches pdf to try and get rid of the problems you can see in the attached image around the ceiling raft and on the column. I've set indirect caustics to none and visible to indirect rays un-checked for the ceiling material. I'm rendering using interior best but still having problems. Any suggestions? I've attached the dgn.
Microstation 08.11.09.459 Windows 8 pro
It almost looks like there may be some co planar interference, happening at the ceiling raft.
Regardless, assuming you are using area lights at that condition, you might try jacking up their shadow sampling.
If you don't have geometry interference or low shadow sample lighting, you could try creating an Insane setup, with higher indirect bounces and/or irradiance caching.