I recall one day, I had a similar issue, I had to uncheck the box, run Orbiter, then recheck the enumerate box back again. It was a time I was messing around with multiple monitors.
Otherwise, check the graphics card, the drivers, and that directX and opengl and direct draw are all correctly installed and running. If there are any faulty installs it can cause something else to go wrong (generally speaking)
DirectX is available from Microsoft for free.
Are other 3D games working?
What is your graphics hardware?
If you have no graphics card, then the system will fall-back on the built-in Intel Extreme Graphics 2. This is the same style of chip I have in my old laptop from 2003. Cool!