Well, if your game is showing a res and its not setting to screen correct, have you made sure its using the native resolution dimensions to the monitor first off all? Have you made sure you dont have any screen W/H position overrider settings in your graphics driver display settings? And have you also made sure that even all of that being ok, that you dont need to now adjust your actual monitor H/W and position setting to stretch or uniform by the physical button menu options of your monitor?
I know that my monitor can display off center when games kick in, If I align and set it via monitor, desktop display will be ok and untouched but it will jump to that setting when graphics changed as game re kicks in to align and match.
Apart from that, I dont have your game manual, no one knows your graphics driver or card, and no one can see what your see so in actual fact:
What? More in details please...
Is quite Ironic.