Here's what happened, as close as I can figure it: I reached the scene in episode 3 ("Long Road Ahead") when I'm going to confront Kenny on the train about Duck's condition. Except I couldn't make my cursor click on the door leading out of the passenger car to Kenny. It simply stopped moving to the right, with the door's "button" just out of reach.
The problem persists no matter how many times I save from a different point in the episode, or reboot my PS3....which means I can't progress in the game at all. What can I do?