I have Windows Vista and my Dell desktop can't get out of the blank screen. For a few weeks it would take a while to come out of hibernation but now it won't at all. No mouse either. All I get are occasional vertical lines that flash every few seconds. I've tried turning the monitor and computer off and on, even to the point of unplugging them. When I turn the computer on I can hear it booting. In fact, I was able to use my password to start Windows Vista even though I couldn't see anything -- could only hear it. My monitor is an Acer AL1912, about 4 years old.
Does anyone have any idea what the problem and solution could be?