either you may need to adjust the gamma correction, or one of your monitor guns is flaky is the most likely. however, the contrast setting for some monitors can bring up the green a fair bit especially on dark screens/images. or it may be that your green sub brightness is in need of adjustment. this and the first cause are STRICTLY THE REALM OF QUALIFIED REPAIRMEN. THERE ARE LETHAL VOLTAGES INSIDE YOUR MONITOR EVEN WHEN SWITCHED OFF AND UNPLUGGED. sorry for shouting but ZAPPED TO DEATH is not good.