I found this forum while searching for an answer to the 'Astronomical Zone' output in my GV. This is my 2nd one of these with lots more gadgets. I noticed the warning yesterday while travelling between Birmingham and Manchester in the UK.
Suddenly both warning lights come on and a message appears in the dashboard. After about 5 miles everything went back to normal. On the return journey about an hour later the same thing happened on the same road at the same spot in the other direction.
Seems like it's an external influence. What causes it?