Viz Help Again

[architect-sma]

I have been recieving help from a number of users in the last few days about a MR problem. They have been a help, however now I am having another problem with final gather. It was first suggested to me to increase my number of photons and manipulate the radius so as to get good lighting. By just manipulating these setttings I should be able to get a rendering which is almost complete, then I add a "little" Final Gather to fix any other dark, blotchy areas, etc. Please refer to the two thumbnails I have attached. The first image is w/o FG and is of fairly good quality, I should only have to add a little FG to make it final. However, when I add the FG (second image) the image gets those weird squares of different light qualities on the walls and floors etc. I know it's not the bucket size because the bucket is at its highest setting of 512. Anyone have any other suggestions for the final gather? Any help is appreciated as I am running into a deadline here at work on Monday.