If you are getting NaN shown as a solution, then you have a bad value in your gun profile. For instance, the bullet length is set to 0.000. This also confirms that you have an older version of the firmware as later versions will check for these conditions before loading the gun on the unit. Check your profile and update your firmware to resolve this issue. If you are getting Bad Enviro as a solution, then there is an issue with one of the sensors. If the issue persists, then there might be a sensor failure. The best course of action is to fill out a Kestrel Service request and send it in.