Thanks for the answers, but I still have the problem.
I didn't make it clear: I use a Logitech G27 with Logitech Gaming Software, and no matter what I do with buttons, look left or right does not work. It IS ASSIGNED both to the wheels and the keyboard, and none of them work with the COCKPIT view, but both of them work with any other view. I tried re-assigning them, and still the same problem. But if I press the glance left and the glance right buttons at the same time, it looks back, just like it should. Its really annoying.
And it was working JUST FINE, and out of the blue, it just doesn't work anymore. I didn't even closed the game: I was playing, and then, when I restarted the practice session to switch cars, it wasn't working anymore. I checked that "Lock cockpit camera to horizon" or something like that, did not work, unchecked, still did not work. I didn't install anything, I double checked the "Programs and features" menu in the Control Panel, just to make sure.