After upgrading your video drivers on the M200 to something decent, like the Forceware 98.16 drivers, the automatic screen rotation will cease to function. However not having the screen auto-rotate doesn’t spell the end of the world. To correct the orientation of your screen simply press Windows key + X to open the Windows Mobility Center. Once the Windows Mobility Center opens, press the R key until the screen is in the desired orientation.
If you want to change the sequence of the screen rotation, go into your Control Panel and find Tablet PC Settings. Near the bottom of the window there should be a link Go to Orientation, and in there you can change or remove rotation sequences. I’ll also have to suggest that you calibrate your screen, if you haven’t done so already, before you rotate your screen. To calibrate your screen with your pen, press the Calibrate… button in the Table PC Settings window and follow the instruction.