The weirdest thing happened today and I need help understanding and preventing it. I have 100+ flights with zero accidents and have read all manuals, forums and thought I had understood everything regarding the Phantom. Yet today... 1.I went out of my office on the street for a break 2.I armed the phantom, waited for compass and gps 20-green flashes 3.Took off and tested the GPS point to make sure it's recorded. 4.Took it out of range to test the range - and it started coming back on it's own as expected. 5.As it came closer, took control back. Went a bit far away again, this time not out of range and headed back to land. 6.And the craziness began : as the phantom approached above the office building, it started acting weird. Was circling in circles, with little control - and soon I completely lost control. Controller was in GPS / HL/CL-off setting; was on, I did not turn it off during the flight for sure. But there was no connection. Phantom started making circles near the top of the office building. This continued for quite a bit. It seemed as it was holding the level, just circling around. After some more time it finally hit a chair on the balcony on the last floor and got stuck. I was running around, searching for it, then went on the last floor and found it. It was still on, one of the props was jammed in the chair. I removed the Phantom carefully, as it was obvious it will keep running - which it did, it turned back on all 4 props and was trying to maintain it's level successfully. I was not having any connection between it and the remote. 7.Took off the battery; which was super drained at that point; but just to make sure - reset the controller, put the battery back on and tried - there was OK connection this time. A hint may be that when I returned back to the office floor (same building, two floors lower); I was told that the internet (Wi-Fi) had went off at some point; seems like at the same point while I was flying my phantom and lost connection. What could be the explanation? Is there a cure? Would this randomly happen again; or was there a logical cause for it? Thanks!!!