I am using Mac OS X Lion 10.7.4 on my Mac mini, with Samsung monitor with default resolution 1360 x 768.
My Mac mini is connected to Samsung VGA port by Apple mini port to VGA adapter.
When starting, my Mac does not recognize the wide screen resolution and always starts in a 4:3 mode, (but it shows 1360x768 as the resolution in the settings). I have to do one of the following actions to bring my Mac to the wide screen resolution:
(1) Changing to some other resolution and bring back to the default resolution.
(2) Unplug the Apple mini port to VGA adapter and re-connect again.
(3) Put the machine to sleep and wake it up again.
I am using Ubuntu 12.04, (in a different partition) in the same hardware, but Ubuntu is perfectly recognizing the display.