Please try the steps mentioned below and reply with results:
1. Check if the lines on the screen appear on Dell Logo and in BIOS.
2. If same issue is seen on dell Logo and in BIOS, Follow Outside OS troubleshooting mentioned below, else follow Within OS troubleshooting.
Outside OS Troubleshooting:
1. Check by connecting a known good external monitor.
2. If known good monitor works fine, the problem is with the LCD panel. Else, follow next steps.
3. Run LCD BIST (Built In Self Test). To run LCD BIST power on the computer using the D + Power button. The color pattern should be displayed. Check if you can see the lines during the test.
4. If the lines appear during the test, the problem is with the LCD panel. Else follow next steps.
5. Run Dell 32-bit Diagnostics. Click here to find steps on how to run Dell 32-bit Diagnostics.
6. Run Custom test on Video card.
7. If the test fails, replace Motherboard. Else, follow Inside OS troubleshooting.
Inside OS Troubleshooting
1. Run MS Fix-It : Solve Windows display quality issues
2. Download the updated video driver and BIOS from the support site. Uninstall current video driver and then install the updated Video driver and BIOS which are downloaded.
Note: Plug your computer to a good, working UPS before you update the BIOS. If you experience a loss of AC power or a significant voltage sag/spike during the BIOS flash, you will either have to buy a new BIOS chip or buy a new motherboard.
To know more about Dell's products, services and drivers & downloads, please go to http://dell.to/YBlak6