I have noticed when I am building lots that my screen will sometimes flash ( see pic below) This has also happened in the neighbourhood view. It only happens for a few seconds than it is back to normal. I have no custom terrain paints ( I had issues with them in the past) The only hacks I use is ones I downloaded from here. Sims is the only game I play so I am wondering if others think it is a game issue, or a graphics card issue.