I'll throw my 2 cents in here. I'm willing to bet all the people having this problem have logitech mice ( or at least mice with some sort of control panel software akin to logitechs setpoint software.). Try uninstalling your logitech setpoint software and just use windows regular mouse properties to control your sensitivity, I bet the problem will go away. I used to have this in all my fps games with all versions of logitech setpoint on my G5, controls locking up anywhere from 3-5 seconds, the moust seemingly moving on its own. uninstalled it and it vanished.
*edit* even if you dont have a logitech keyboard i believe it can and will still mess with any keyboard. not 100% sure about that but i think it has something to do with the setpoint software hooking into the application