I have a drawing with contour lines in it that are at the wrong elevations. For ease of use, I wanted to have them all on elevation 0. I had my floor plan on the contours when i invoked the command. When I selected all the objects, it asked me to "Remove hidden lines?". I said yes. When I hit enter, it completely screwed up my floor plan.
I have since gotten around this setback. I was just wondering if anybody knew why it did this.