Try to delete the system.cfg and SystemGraphicsOptions.cfg (or better just rename them as OLD or something or move them elsewhere as backup) if they do not exist in the game folder the game will basically create new fresh ones to reset settings and see what happens. If it doesn't fix your settings you will need to modify the SystemGraphicsOptions.cfg manually and put it on read only so that the settings stay fixed. The settings there mirror the ones in the graphic settings, if something is a checkmark it's either 0 or 1, the sliders go from 0 to 5 I believe. There is also a thread about adding other lines to smooth the gameplay a bit and gain more fps if you are interested.