I have flashing images across my screen especially playing videos

I asked for help with another issue
(Question https://answers.launchpad.net/ubuntu/+source/xserver-xorg-video-nv/+question/214301)
because I was having trouble booting up and getting an error screen saying "the system is running in low graphics mode" now after cutting and pasting commands to solve the problem I am getting flashing screen images especially when watching video so it looks like there are ghost images to the right left and above and below making the video all but unwatchable.