I have solved Dirt. However, my main problem is, at first launch after installation, all games are in 4:3 aspect ratio
lol sorry but that's really funny !
it's all pretty normal behavior, the first thing to do in a PC game is to go in the options and set it up for your liking/hardware ...
it's not a console ;)
and unless I don't change from options, the screen sidea are cut.
that's because your screen & driver are keeping the aspect ratio of the resolution, which depending on point of view can be a good thing....(edit: I, actually setup my screen to display unscaled resolutions only. that way I don't have to deal with ugly scaling nor ugly stretching ... but I have black bars with some games which don't support 1680x1050)
it's like the black bars for 16:9 movies on a 4:3 TV ...
if your screen is DVI equipped, your ATI gfx card should have an option for default stretching to native res, look in the Catalyst Control Center.