"Phantom" Ceiling Plane

[coogan]

In the attached JPG (I had to make it smaller in order to attach it), note the gray diagonally-oriented surface. This artifact suddenly appeared as I was editing a plan (changing the default ceiling height of the first floor) and trying to get a skylight dome to appear correctly. At one point I had inserted a custom ceiling plane, but removed it. The rectangular area on the right with the glass block front should be open to below, as should be the square area (bounded by the short walls) to its left.

This artifact is, in fact, a ceiling plane, because when I turn on "Use Above Floor's Platform for Ceiling" in Floor Defaults, it goes away. That may be OK for this small test plan, but I've dealt with this "feature" before, and I can't always just turn off ceilings. It IS annoying, and I don't know how to keep it from happening, or to get rid of it any other way.

The plan file (it's just a test case) is small, so if you'd like to see it, I can send it so you can observe this behavior.

My vital stats: Home Designer 6.0 Pro, version 6.03. Dell P4 2.0GHz, 1GB RAM, NVidia GeForce4 Ti 4200 w/64MB, latest video drivers and OS patches.

Thanks.