Could just be a loose cable to your screen... laptops are prone to that because they are always getting opened and closed, and that joint there is where the connecting cables are. If its under warranty the manufacturer can probably fix it. You take out the hard drive before you send it so you won't lose your stuff.
Or you could take it to your local Geek Squad and have them see whats up =P They'll tell you if it needs to be sent in (hardware problem) or if they can debug it (software problem).