I had my monitor hooked to my Dell desktop. right in the middle of working, the keys all froze. No mouse or keyboard action. I pushed the power button to turn the computer off, then tried to reboot. The computer comes back on but the monitor screen is black. I tried connecting the monitor to my laptop and can get it to come up in safe mode, but it won't come up in normal or with last known. I can't determine if the computer is on the fritz or the problem is in the monitor. Any suggestions?