It sounds like you may be talking about the monitor refresh rate. Go into your display properties,click the settings tab. Near the bottom of the window, click the advanced button.This brings up a new window, click the monitor tab and you should see something simular to this
Be sure that the Hide modes that this monitor cannot display is checked, then you can safely select a higher refresh rate from the dropdown box.
Hopefully you can translate my bad english into your dutch xp


