What would cause the power settings (turn off monitor after so many minutes, put PC to sleep after so long) not to work? We have just installed Vista Home Premium, and none of the settings seem to ...

Ok, at random points, even during bootup, the monitor will shut off, it won't power down, but the screen will FADE to black.....it doesn't flicker off, it just "voosh" and it's black, if I turn it on ...