Current Setup: P2 package W/Zenmuse H3-2D Gimbal, GoPro H3 Black. Mini IOSD, TS832 600mw FPV TX, Blue Beam Ultra FPV TX Antenna. Location is Los Angeles. Flying locations have been Deserts, Parks and various Country Clubs all over Socal. Since day One very first flight. (Pretty windy conditions on that one) I have been having this issue that when I fly forward in a straight line, the Phantom 2 begins to drift off course to the left. The nose will remain pointed at pretty close to the same initial heading but it as if I was adding a bit of left roll to the stick which i have made sure that I am not. I have tried it in NAZAM and Phantom 2 modes. II have tried different gain settings with no change. I have had the Phantom for 6 weeks now and it has done this since day One. I have flown it in 15-20 mph winds and I have flown it in 0-5 mph winds and there is no change. I had a hard landing with tip over once but there was no visible damage and the props were also untouched. It flew after that with no problems. except this drifting issue. All my firmware updates are good. Advanced IMU Calibrations have been done and those numbers are in the middle of the acceptable range. Sticks calibrated and pitch checked to make sure there is no roll input when adding pitch. Compass calibration gets done every new location I go to fly. I do not have anything in my pockets and my cell phone is turned off and in the car. I have been talking to the dealer about this and had one of the really knowledgable Quadcopter guys come and fly it yesterday. It was really doing it when he flew it and the shop he works at was up the street. We went back to the shop and called DJI. The tech at DJI couldn't come up with any ideas and said we already went through all the trouble shooting steps. He told me to send it in for repair. After negotiations with the owner of the shop I got him to replace the P2. We took the new one out in the back of the shop (without my Zenmuse, iosd and fpv gear installed) and flew it. It also had a slight drift to the left though not as bad. Another guy at the shop had a Phantom 1 with nothing installed on it and his Believe it or not his also had a slight drift to the left. Everybody is stumped. He then looked up at the sky and blamed the GPS Satellites for the problems. I know the gov't can through in any amount of error they want to the GPS system but that seems pretty unlikely as it would disrupt life as we know it. Anyone else experiencing similar issues?