This is a copy of the e-mail Garmin sent me today.
Thank you for contacting Garmin International! I would be more than happy
to help you with this today.
Seems to that when you are navigating to a waypoint that the unit is
actually trying to use two different data inputs for the same information.
With the compass on the unit wants to use the compass when traveling less
than 2.5 miles per hour. But above that speed the unit then switches to
satellite compass information. This is known by our engineers who are
working on a fix. Thanks for your input and thanks for letting me know what
you found out!