Why doesn't my resolution correct itself when I change the resolution in a game?

[B-Bud]

For some reason, every PC game I have that isn't made by Valve has this strange problem where whenever I change the resolution of a game to something lower than my native screen resolution (1920x1080), instead of the game screen reaching all edges of the monitor like it's supposed to, it just scales it like it's in windowed mode, except instead of a window and some desktop, everything other than the game screen is black.

It looks like this:
[img]http://u.cubeupload.com/berniebud/THISINSTEAD.jpg[/img]
Instead of this:
[img]http://u.cubeupload.com/berniebud/OFTHIS.jpg[/img]

Specs:

OS: Windows 7 64-bit
Video card: ATI Mobility Radeon HD 5470
Processor: Intel(R) Core(TM) i5 CPU, M 480 2.67GHz
RAM: 4.00 GB

[editline]February 22, 2013, 1:53 PM[/editline]
Sometimes, a game will be properly fullscreened, but I have no idea what causes it to do that.

[B-Bud]

[QUOTE=Amiga OS;39679580]Check your catalyst control panel for a video scaling setting.
My Thinkpad has the option to center the screen at lower resolutions or up-scale it.[/QUOTE]

I couldn't find anything in there.
I'm not sure if that would be it, because sometimes a game will be in proper fullscreen.
I don't know what causes that though.