Have you tried the checkbox 'Show All Resolutions' ?
I see you did not check that check box in the screenshot. I'm guessing you already tried it tough
Also:
- if you reinstal the game without reinstalling the dlc is it possible to select a resolution?
- have you tried updating the game?
- have you updated all your drivers (specifically video drivers)?
Other than that I really wouldn't know what could be the problem :S