Anytime I run Maemo Mapper the N810 begins searching for the satellites. From what you said I'm assuming you've gone into the menu option on Maemo Mapper and have Enable GPS checked? If you go to GPS Location Settings is Enable GPS checked and GPS Device is set to Internal GPS.

These would be my first guesses if you haven't already done so. On my device I never had a problem with it not starting the GPS. Only problem was getting a lock right away, which was partly solved with AGPS.