Ignore Bluestacks, it SUX big time. This seems like a GFX issue, so try this (just make sure to follow all steps in the right order, even if you've already tried some of these before):
1. Clear your application cache
2. Click System settings
3. Click Performance settings
4. In Graphics rendering mode, you have the choice between OpenGL and DirectX.
5. If OpenGL is selected, select DirectX instead / If DirectX is selected, select OpenGL instead
6. Save settings and restart NOX.
7. Launch the game...and cross your fingers. Hopefully the black boxes should be gone now :)