Sorry guys to bang on, but the GPS part has caught my interest. Anyway for what it's worth :-There are no obvious explanations in the manual which answer why turn it off, especially on short final. I'd love to know where it was mounted, purely for interests sake.
The only information of any interest was on page 60 where there is a 'flashing' alert system which may have been distracting. (Messages/Time offsets page 60).
Altitude Field page 18.
Screen Backlighting Timer page 46.
Mounting the GPS page 53.
Power connection page 59.
Back to the drawing board for pet puzzles.