I have a growing black horizontal line on my.... Hello,Last weekend I noticed a small glitch on my

Question

Hello,Last weekend I noticed a small glitch on my screen. It was a small black horizontal line in the lower right side of the screen. I figured it might have happened from my 18 mo old doing something to the screen. But now it is growing! Over the course of the week it has gotten 3 times as big. It is about an inch and a half in size now. What could be causing this and what can I do to fix it. My computer is out of warranty so I don't have many options there. Thanks, jamkr9