I've experienced this with another system but only after previously hitting the ground through operator error. Turned out that crash induced damage in two ESCs that had hit the ground that was not apparent until after they had later been in use long enough to get warm. The next crash was due to damaged ESCs. Replacing the ESCs corrected control issues.
Something to keep in mind, electrical components built on PCBs are not impact shock tolerant, especially when such impacts impart considerable kinetic energy. They can easily sustain damage that may not immediately become evident. A good crash requires considerable ground testing before putting those components back into the air. Many of us have ended up spending a lot more to repair subsequent crashes because we hoped to save money and reuse previously crashed components lacking visible evidence of crash damage. If we threw our laptops across the yard and they hit the ground as hard as a multirotor we would not expect them to function afterwards. I'll venture the component quality in most laptops is better than what we are provided in multirotor components.
There's also the possibility you have an older Naza. Some of them had a propensity to periodically go into the "flip of death" for no apparent reason.
