I was taking a few pictures with my 5D Mark II and everything was great, then I changed the lens and the camera wouldn't fire anymore. Switching back to the other lens didn't solve the problem. The camera focuses just fine when I press the button. I can even shoot videos with liveview, but the camera refuses to take any photo when I press the button.
I did reset the camera (removing both batteries) without result.
Any hint would be great! It doesn't look like something is physically broken. Antony