First of all I'm using Mikrokopter boards on my CS8. Last weekend I decided to shorten all the motor cables and run them outside the booms so the copter would be faster to assemble. Everything went well and I also moved the gps/navi boards from boom #5 to boom #1 as people have recommended. I got the Cinestar as RTF package so the builder had somehow decided to put the compass on boom #5. So prior to these modifications everything worked great. Today I went to local football field and did the compass calibration following the instructions from Mikrokopter.de. I heard all the right signals and I think everything went well again. So I did my first test flight and the copter was really stable and flew nice and smooth, altitude hold was solid but after that I tried position hold. Whoa! My CS just rapidly tilted towards me and started to fly with speed and I immediately turned PH off and was able to save it from crashing to the trees, it actually chopped couple of small branches off It was really really scary. Other than that it flew perfectly. After that I drove to another spot to do the compass calibration again and got the confirmation sound again. (front boom was facing North both times when calibrating) Tried the PH and the same effect, just tilted rapidly and started flying fast towards me. So did I do something wrong when I moved the GPS board or do you think the calibration failed both times? Also I just started to think I might have accidentally rotated the GPS board when I was moving it to boom #1 or does this even matter? Before these modifications PH used to work good. Thanks!