Depending on the issue. It could be dead pixels. Try to take a warm cloth and gently press on the areas that are having the issues. It may be a firmware issue as well, I have posted a link to a youtube video to help you with it (if its what it is)
http://youtu.be/9DPcZ1LBxf8
I would also say it could be an internal problem, where the wires are a little loose. If you have the proper tools and it will not mess with your warranty, I would take it apart and check the connections.
If none of these work. Try taking it in to get repaired. But Id guarantee its one of these.
Corey