Do you have two monitors connected? If so, selecting the wrong video device (monitor) will cause a white screen on startup. Please check your video settings in the Orbiter Launchpad and select:
* "Direct3D T&L HAL" as the 3D device; this will always select your primary monitor, which is particularly important in dual-monitor systems but also works in single-monitor systems.
* "Full Screen"
* Set screen resolution to your primary monitor's native resolution (usually the highest resolution listed in the drop-down).
* Set color depth (bpp) to 32.
* Ensure that "Disable hardware pageflip" is checked.
Now launch the default "Delta-glider\DG Mk4 in orbit" scenario. Orbiter should load normally and you should see the Deltaglider's 2D instrument panel appear.
If that does not work, please post the contents of your Orbiter.log file, which is in your top-level Orbiter directory (e.g., C:\Orbiter).