Do you have a button marked "Auto" on your monitor - this sets it to it's default setting.
Have you had a look at your screen resolution/colour settings.?
Have you tried to adjust clear type text? Right-click on an empty space on the desktop and click on Personalize. On the bottom left click on Display and then on the left you will see Adjust Clear Type Text.
You will also see in the same panel adjust resolution and calibrate colour.