I am trying to connect a Samsung 22" SyncMaster with my laptop running Windows 7 32-bit, an AMD HD 6500 Mobility. Though Catalyst Control Centre as well as Windows identify the correct resolution of 1650x1080, and it is selected, it isn't displayed. Looks more like a lower resolution that's getting stretched over the monitor. The weird part: The monitor worked for years without problems, one day it decided not to work properly anymore. Maybe some update issue, I have no idea.
I believe this issue is due to the Samsung screen's auto adjustment feature. My problem occurred when I hit auto adjust by mistake and the screen attempted to adjust the picture to fit the screen, although it did not have enough information to do so. (My background image, like many, does not fill the full screen. The monitor made the assumption it did and attempted to rectify the problem by stretching my background image and thus messing with the resolution in the process).
Putting something full screen with lots of detail (like a browser page) on the misshapen screen and then hitting auto again (right next to the power button on the screen) resolved the issue for me.