Windows Phone Emulator requires a DirectX 10 or above capable graphics card with a WDDM 1.1 driver. I assume that you got an error message on first start of the emulator that your graphic adapter isn't capable for all functions the emulator
If your graphic adapter does not fully support DirectX 10 or doesn't has a WDDM 1.1 driver you will only see a dark screen instead of the rendered webpage. This also affects all controls using MultiScaleImage, including the webbrowser control. As far as I know there is no solution for this at the moment.
Link for
Dx 10