Where Dell Flat screen 15"

Question

Where Dell Flat screen 15" monitor has not been used for a period of time or on boot up the screen displays for a seond then goes black (although in a certain light you can see the icons and programs in use). If you switch the monitor off and back on again the display appears for a second and goes black again. If you complete this around 30 to 40 times then the display appears fully lit up.Throughout this time, where the monitor is switched on, the power button appears green