Windows Phone 7 emulator doesnt work properly and just flickers

Windows Phone 7 emulator doesnt work properly and just flickers

Windows Phone 7 emulator doesn't work properly on my laptop. It just
flickers instead of starting my app. Clicking on any of the buttons has no
effect. (None of the emulators work, tried 256MB, 512MB, and the ones
installed by WP 7.8 SDK Update) WP 7.8 SDK Update didn't solve anything.
I'm using a Samsung NP300E5A-S06 notebook, and it has:
Core i5 3210M 2.5Ghz
Intel HD Graphics 4000 + GeForce GT 620M
6GB of RAM
Here is a video of what's happening on my machine. I heard this can be
caused by the Intel HD Graphics 4000. But we can't force WP Emulator to
use the GeForce.
How can I make the WP7 emulator work properly?
If you have any idea or a working solution, please help me! Thanks in
advance!