thanks DominicD for your help.I have win 7 isntalled.I opened that settings page u told.There my monitor's refresh rate is set to 60 hz also there is no option above this.Second option u told that is "Hide modes that this monitor cannot display" is not available to check.Pls see the image.


You can also see above that monitor name is "Generic PnP Monitor" while my monitor's model is "Samsung B2030".Can you tell me whats wrong???
Also before LCD i had an CRT.That was fine.
Thanks again!