Monitor showing color test after staying on overnight

[Agamar]

I have an AOC 19" monitor and if I leave the computer on overnight, the monitor will occasionally start showing the color test, and will refuse to turn back on. I have replaced the video card to see if that will work, but the machine is brand new. Anybody have any ideas of things I could try. I am thinking powersaving if it turns out that the video card was ok.

 

[Train]

i used to have this problem with a gateway, the sleep mode thing they have never works, would go to sleep and never wake up. turn off any sleep mode stuff if possible, then if the monitor goes off, move the mouse, hit a few keys, wait a minute, it should be back on, or turn the monitor power off then on again