Twice yesterday I had a problem where the screen would just turn black but the game was still running in the background since I could hear the sounds.
It wasn't a crash per say since I could just alt-tab to windows just fine and go back into the game without issues as well(but greeted by the same black screen).
I had to alt-f4 just to get out of the game.
Can point out that both these cases occured while talking to a NPC.