Computer Monitor Screen Black/Green Light

Hello, I own a Dell LCD Monitor, when I boot up the computer the monitor stays black. I see the desktop image for half a second, but very faintly. The power light is solid green and remains so. I have switched out monitors, any other monitor works fine. I also switched out power and VGA cables and its not any of those either. When I press and hold enter right after I turn on the monitor, I see the desktop image again faintly, but it disappears in half a second. What's the issue here? Thanks again.