No idea (probably a combination of the monitor (screen) and the placebo effect).
Why not just run at 59Hz?
Also had this problem with a Samsung monitor, its the colour profiles. Really irritating how Samsung seems to think you want to have a strange tinge on you monitorCould be to do with colour profiles. They changed the way they work in Win7 and it can have some odd results.
One thing to try to see if your colour profile is wrong is view a picture with the Windows photo viewer, should be the default viewer unless you have changed it, and see what colour the background around the picture is. If it is a brownish/yellow colour and not more of a blueish off white then it's wrong.
Have a google around but it seems to affect Samsung monitors a lot.
Have you tried a different cable?
A faulty on can cause a green tinge. On the Samsung i had problems with, occasionally the screen would wobble very slightly and that for some reason was caused by the cable, although it worked fine on another Samsung monitor which was rather odd.