Hmm, not something we've seen before. If you have more details we can look in to it. Do you have a wireless mouse, did you play in fullscreen, did you have decent framerate? It might be an issue on your side, but if not we will look in to it. :)
I had the exact same problem. I went into options then controls and for some reason sensitivity was turned down to 0. I turned it up and it was fine. I'm guessing that's the same thing that you are experiencing.
