Well I'm glad to have given a little insight. It took me forever to figure out why my machine was doing that but I was easily able to duplicate the problem while attempting to stream.
I haven't been keeping up with things to know if there are any optimizations in the works but hopefully your problem is being looked at. If not you might want to try and find other players who share your problem and band together to move it up the chain.
Good luck!
I have a 360 controller also hooked up to my PC also, and was able to instantly fix the behavior by tapping the controller (which never stopped working) and then going back to the mouse (which suddenly started working again.
