The screen freezes and becomes unresponsive to the touch.

If you are in a location that where it is difficult to receive a satellite signal, enabling GLONASS can provide more accurate activity tracking. Also, if the watch has its auto pause feature turned on, it may be unable to sense and record data for the particular activity and pace. Lastly, you should also check to ensure that any accessories (like a heart rate monitor) are correctly paired with your Vivoactive. For more information, refer to the troubleshooting page: Garmin Vivoactive Troubleshooting