How powerful is your video card.First of all check that does your video card supports that high resolution.If it does then please update your video card drivers and also install your monitor drivers which would have come with it.
I Just Bought An Envision G22LWk Monitor. I Have A Dell Dimension PC. The Recommended Resolution For This Monitor Is 1680X1050. The Screen Properties Do Not Allow Me To Select This. I Am Trying To Locate The Driver For This.