Thats weird. I went back to the computer (monitor was in sleep mode) and it looks fine. Maybe the problem starts after using the PC for while, meaning when things get heated up. This leads me to believe it may be a video card issue. Ill post pics when it happens again.
A defective screen will be evident no matter what is displayed, a defective graphics card will be evident at certain times typically. If you don't see the lines shown at startup then it would be the graphics card. I would try booting Windows into Safe Mode with F8 and possibly install a newer version graphics driver. If the problem persists and the card looks in good condition then replace it. Some graphics cards with these issues are overheating because they are caked with dust or they the fan is no longer spinning.