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Can you try to connect an external monitor on your computer? Use a VGA cable to connect it. Then see if the same lines appear on the monitor. If no lines on the monitor, possible this is a hardware issue. Could be the LCD or the the connection inside the laptop. Here is the link for the manual http://dell.to/Jug2gg You can check for loose connections inside. In your case you need to remove the Keyboard, for you to access the LCD cable connections.
Let me know if you need further assistance.
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