Hadn't done so before, but now have tried shaking it...upright, upside down, sideways, etc... Also, tried tapping each corner of the laptop gently on the desktop. No flickering of any type. It doesn't act like a loose connection or wire. It is is very consistent. It seems more like what ever makes the screen go into the sleep mode is set at a second instead of "minutes." During start-up, and while the computer is running, if you press down the button that shuts the screen off when closing the lid... and then let it up...the screen comes on perfectly for a second or less, and then goes off again. By repeatedly tapping the button quickly, I can see it well enough to use the mouse to shut off the computer properly. So far, I have not come up with a plausible reason for it acting the way it does. Thanks again, Dan