Hi, I've only had my Phantom 2 a couple of weeks, so I'm still getting used to its idiosyncrasies, but I've just encountered an issue that I haven't been able to find an explanation for. Having set the Phantom 2 up and waited for the GPS green lights to flash I take off, but the Phantom 2 doesn't hover particularly still and drifts around. Once in the air the lights flash green several times normally, but it then flashes red a couple of times and then goes back to flashing green and so on. The battery is fully charged. The Phantom doesn't drift as much as when GPS mode is off, but it doesn't stay in place the way it does when GPS is working well. I'm not sure what the issue could be as it's not a sequence I've been able to find an explanation for.