One thing that is very important when using TurboFLOORPLAN is that you do you best to clean-up and sloppy intersections. This includes ovlapping walls or areas when one or more building elements overlapping, such as a floor, wall, roof, ceiling combo. The cleaner you can make the interaction of those element the better your drawing will perform. In general try to draw it like you would build it.
In the "File" menu there is a "Repair Project" feature which should be used as a last resort. However be sure to back your drawing up because this will in some cases deleted the corrupting elements in your drawing.