I've found that when I try to place some objects, they automatically flip 90 or 180 degrees. For instance, I select a chair from buy mode, move it against a wall, click to place it, and it flips in a different direction. I haven't experimented enough to know if this happens with every object or just certain ones.
Also, I tried changing my input device (went from laptop touchpad to a mouse) and that didn't make any difference.
