Now the following has happened to me quite a few times with different codes. Latest code I've tried is 2.1. APM is version 1:
I'm hovering in stable mode. In flight, the quad just tips over and crashes. After that, one of the motors is squeaking loudly without rotating.
Moreover, the arducopter does not respond to any stick movements. The leds are on, but I'm unable to disarm it. I need to disconnect and reconnect the battery to get it responding again.
Any ideas? Faulty APM?