I'm currently running 14.04 beta on a Lenovo Thinkpad Twist (s230u). As the OS boots into the login screen, the built-in mouse and keyboard are disabled. The touch screen remains active, however.
I've found a way around this: using the touch screen I reboot the system. As it boots for the second time, the keyboard is functional. The mouse however remains inactive until i log in.
I've experienced the same issues on 13.10. Any help is appreciated. Thnx!