Dell Studio 15 laptop displaying red and green lines inconsistently

Hello,
I have green lines that are on my wallpaper. They disappear when I hit the start button on the taskbar. I also had red lines appearing when I ran different windows, and it seems these red lines are confined to a specific area of the screen- in fact the green lines seem to be too, but they disappear when I hit the start button, that's the odd part. Do I need to replace both the screen and video card, or may this just be a screen problem alone?