Is the sensor on your kinect accurate enough or do you have some problems when you move. Mine works fine but I have friends who are not that pleased. Maybe they installed it wrong?
I don't have a Kinect yet, but I have used one at a friend's house several times. While it's not perfect, I'm satisfied enough to want one, ha ha!! It's definitely better than the sensor that comes with the Wii.
Don't know what's wrong with yours, maybe some installation issues or even some malfunctioning. You should try re calibrating it again, you probably did something wrong. Mine works just fine.
I played with my own and works fine, played at my friends' house and also works OK. If re-installing the thing doesn't work try contacting the warranty people and maybe change it if possible. It should be working, I had no problems up until now.