I have had the Phantom for a week now and am on my second unit; had to return first Phantom to B&H Photo for an exchange which was not a problem. What happened was this: on my second day and 6th flight, after taking off in GPS ATTI with 6 or more satellites locked and rapid green flashes recording home position prior to takeoff, the phantom suddenly pitched forward after afew minutes of perfect flying performance/response and dove into the ground. Fortunately I was only flying 3 or 4 feet off the ground (grass field) at the time and there was no damage at all. Subsequent attempts to fly were a no-go as it would only stay in Atti mode (despite right swirch being in GPS mode) single yellow flashes, no green lights ever even after complete IMU advanced re-cali and compass recalibrate. I connected to the Naza assistant software and the GPS appeared to be "dead" as there was no GPS information under the "Upgrade" tab on the assistant, just dashes under "loader", "Hardware ID" and "Firmware". The Phamtom had not crashed or had any hard landings in prior flights. I opened up the shell and all cables were connected to the GPS module, it just failed. This is disconcerting as it could have happened at a much higher altitude or at greater distance when I might have needed to rely on RTH. Anyone have a similar experience?