I think it's a drivers issue in that case.. I'm using modified graphic card drivers because the card isn't windows 7 compatible. (Geforce FX5200 Go)
As soon as I switch to portrait mode, the border with the buttons rotate, but the graphic part doesn't. It floats somewhere on the screen in orientation mode. I'm very happy with the performance, although I'm not sure if the program will need more resources once connected to FC2.0