Generally with things of this sort, it's a graphics card driver. I would suggest updating your graphics card drivers if they are not already on the latest version. Although, with nVidia cards, the 19x line was having a lot of problems in various games (AI War and many others) on some cards. With my 8800GT it was fine, but with some other cards it was a big problem. So, if you're in the 190s on nVidia, you may also want to try downgrading to the 180s to try that you.
Hope that helps!