I have a really weird black shading on all object in viewport. If I drag material on it, it's still black, and the rendered objects color is grey (I added red base color) / What's the problem?

What is your graphics card and driver version? If you're using a 256 or up series driver from Nvidia, you'll currently have to downgrade to 197 (any driver from 185-197 will do).

I have a GF 7300 (OK Ok I know…) with 196.21 driver. S
Houdini 10.xxx works well, so I don't really know what's the problem.
I reinstalled Houdini (11.0.446.9) but still black.
I know that the minimum sys.req is not GeForce, but like I said 10.xxx works well with this card. /

Jeff's comment from another (new) topic solved my problem.

http//www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=20317

I had to turn off the material shader in the Display Options.

BTW, thanks twod!