This happens 1/50 times when I open a website that contains a video. I don't know if it happens when I open a flash video, but I am sure it has happened when I've opened a HTML5 video. When it happens I have about 2-3 seconds to press Alt + F4 (to close my browser). If I do it in time the screen will get back to normal. If I wait too long to press Alt + F4, maybe 3+ seconds, my screen won't get back to normal when I press Alt + F4. However, when I get stuck in the weird screen I can do all types of things on the computer. the whole computer does not freeze, because if I for example press Win + L I will hear the Windows logout sound. I have HD7870, Windows 7. http://tinypic.com/r/3519tf9/5