I've now updated my drivers from those dated 14/7/2009 to a more recent version ( 7/1/2011 ) but I don't know if it has worked or not as I will need to switch my PC on from cold not a restart as the monitor has already warmed up !
'....besides the green and black lines always disappear once the monitor warms up !'
Sorry, missed that bit!
Next time you buy a monitor consider PCBuyIt click here. Most of their monitors (& all the Dell ones) come with a pixel-perfect guarantee for the full 3 years warranty, & next-day delivery for a good replacement.
"All of our Dell monitors are sold with a pixel perfect guarantee for the duration of the warranty period, in the unlikely event your monitor has ANY pixel defect we will arrange for the monitor to be replaced next working day,...."
My old monitor had similar warm up problems. Scrolling problem not lines. But I could cure it temporarily by squeezing the plastic monitor bezel from palm of hand to fingertips (imagine gripping a garden fence)
I never did get round to looking at it, my brother had a spare monitor. Ask friends and family if budget is tight. Or work. Computer Admin may have old monitors in a cup board somewhere.