Computer Will Not Boot Windows 7?

First off, my computer recently had its motherboard/video card replaced. It is a dell xps l501x. The issues with the colored lines began before the mother board was replaced. Thus, I do not believe a faulty motherboard is the problem.These lines are thin and occur on the top centimeter of the screen. They are made up of many colors and sort of look like squiggles going horizontally across the page. Also my computer will not sleep properly. When the computer is put to sleep the screen will go black, but the fan will continue to run and led backlit keyboard will remain on. They begin immediately after the dell logo comes on. I also get 5 bluegreen dots appear in the top left hand corner of the screen.

The lines do not always appear, its is sort of hit or miss with my computer.I have performed a system restore and and wiped the hard drive. This did not remedy either of the situations. I am not sure how to proceed as it cannot be the motherboard or hard drive.