Have a Phantom 2 that I bought new on eBay about a month ago. It had the older version motors and esc's. Had a zenmuse 3D, and my trusty GoPro Hero3 that I have had many times to depths of 100 feet or more in the ocean. I had added a video transmitter when I got it, and had a receiver and monitor attached to my DJI transmitter. Got home early from work so I took it out in my yard and went for a quick flight before dinner. I calibrated the compass as I always do, and had 12 GPS satellites. It had the older style compass, and all firmware updates. I have a iOSD mini giving me the video overlay, which is how I know how many satellites I had locked. All systems go. I took off, got to about 60 meters, and had flown east about 50 meters, as I had done several times before, and never had an issue. I was bringing it back, when all of a sudden I had no control over the phantom. Immediately I tired to bring it back, and also tried to bring it down, but it would not respond. At this time it was heading pretty much due south, at what I would call a high rate of speed. I had not yet switched to naza mode, I still consider myself a new pilot having only about 20 flights or so under my belt. So I knew my only options were pretty much failsafe, or shut off the transmitter. (I recall setting the right hand switch to failsafe in the software when it was switched all the way down). I continued to try to bring it back, running down the street, until it was obvious I had no control, so I shut the transmitter off, running down the street, until I lost sight of it. I had not yet put my name on it as I have barely flown it out of my yard. I live in a rural area with no power lines, cell towers, etc. Not interested in bashing DJI or anyone else, just posting this for informational purposes I guess. If I did something wrong, I would really like to know what it might have been, in 20 flights I never had a hiccup. I am just sick about it, probably the worst thing of all was watching my 7 year old special needs son cry his eyes out. I don't really want to sell out everything I have left, but don't want to risk this ever happening again either. Pretty much all there is to say, it all happened in the span of a few minutes, so I didn't really have a chance to check the readings on the video overlay like I wish I would have. I knew pretty quickly that I had lost control, but I really don't think there was much else I could have done. And also, no real wind to speak of, just a beautiful day. If anyone has any questions, or feels they can help in any way feel free to reply. I think I'm going to have to have a pretty good idea of what I did wrong, that might be correctable, before I consider re-investing. Thanks.