Hi. I've sent my gps back to Garmin (via one of their distributors) because of this very problem. It was switching off at random times almost every flight! They've had it 2 weeks now. Surely they know that the problem is caused by the software update. I managed to get the unit to consistently switch itself off by doing the following: Start gps in simulator mode. Head to panel page and increase the speed of the plane to maximum. It switched itself off every time. When I get the unit back I'll install version 4.1 on it. Thanks for the info.