In the nvidia Control Panel, if applicable, check the Antialiasing - Transparency setting and if it is set to 8x (supersample), reset it to default.

Try resetting your graphics driver's 3D settings to default (right click an open area of the desktop to start the nvidia Control Panel or AMD Radeon Settings).

In the graphics options, Lighting section, try disabling Light Shadows. A few people have reported black blocks covering all or most of the screen, (primarily) in the menu, character creation and the tutorial level, fixed by disabling light shadows (generally caused by the anti-aliasing setting mentioned above).

If that doesn't help, try changing the lighting and shadow quality, or disabling Shadows, etc. A couple of people have reported a similar problem with Lighting quality on high, fixed by lowering it to medium.