This happens every time I start recording a 1280x720 game in windowed mode. So far I've tried with Binding of Isaac (it's a smaller resolution and the problem isn't there, Mount & Blade and LoL (and the problem surely is there every time I start recording). There is a temporary solution to the problem, when I move the OBS program window a bit, but after a few seconds it continues recording like that... I am using only one monitor if that is any relevant information... I have attached a screenshot of what's wrong.