When I leave my computer, I turn off the display and leave the CPU on. When I return a few hours later, I move the mouse/space bar and turn the power on the monitor. Sometimes the monitor light comes on, fades to black and no picture. I turn the monitor off and then back on again and the picture shows. There is no rhyme or reason, sometimes I have to turn off and on 3-4 times before the picture shows. Called Apple, they made me run through steps, but they have no idea what is wrong. Ideas?