A screenshot and complete system specs would be very helpful here.
There are many things that can cause the screen to go haywire. The first thing to look at are your video drivers. Make sure you are running the latest version for your display adapter and maybe check the core temp. Sometimes when a video card overheats it will either distort the screen or cut out all video. There is the possibility of what is called "artifacting" in which your best bet would be to buy a new adapter.