Attached is a custom layout....if you take the upper assembly into cabinet editor, and go into the partition editor, you can see what it looked like before I took out the partition. Hopefully that will give you more info as to what caused it to happen----this is the first point at which I realized something was odd. I had removed a lot of the trims and moldings (display objects and cubes) to study/tweak the details and joinery.
I wasn't planning on using this cabinet/assembly/custom layout for anything more----I brought it up in case there was some underlying program bug that needed to be discovered.