Application has been blocked from accessing graphics hardware

I had the same problem (Application "portal2.exe" has been blocked from accessing graphics hardware), only with Portal 2 rather than Black Ops 3, and after finding no help online, I started messing with settings, and found a fix (at least on my computer).

Open Intel HD Graphics Control Panel -> 3D -> Conservative Morphological Anti-Aliasing -> Turn Off

My computer has Intel HD 4400 Graphics, Win 10 x64, and no other graphics card.

EDIT: Note: this does reduce performance is some games!

I have a fix for those who are running a CLONED TV or monitor. That is your problem. Nvidia helped me with this after a dozen other suggestions this finally worked. I unplugged the HDMI serving my secondary cloned HDTV and just ran the video card on my primary desktop monitor (which is using Display Port cable). Voila !!! No more error message!!! Nvidia suggests if you want to clone a secondary monitor or TV to try using the EXTEND function instead, which I will try when I get the time. But in the mean time just unplugging my cloned TV has eliminated this error message and now I can play my 3d games again. Hope this helps.........let me know!!!