When I first turn on my computer in the morning, the monitor will randomly blink off and on. It will go off for about 2 seconds (at which time the power light on monitor is steadily on), then when the monitor comes back on, I see the "DVI" notification in the upper right hand corner of the screen (like you see on start-up). This blinking lasts for about 5 minutes and then occurs randomly throughout the day. I never get any error messages. Onboard Dell diagnostics showed no problems. Any thoughts? Thanks in advance....