Well that shouldn't happen Zen. Have you checked operation of collective and cyclic. With the motors disconnected does everything work properly. The collective should pull down evenly and the cyclic should work smoothly. If everything is working right it could be the stick sensitivity.

I used a fellow poster's settings with my 7C to get started. I noticed that the controls were so numb compared to the stock set up I couldn't control the heli at first. It needed such exaggerated stick movements. My heli briefly rolled too just like your saying because I didn't give it enough cyclic at first to prevent tail rotor drift then I gave it too much. This lead quickly into a dynamic rollover condition. It doesn't take much. I readjusted my rates after that and it was much better. I actually like sensitive cyclic controls.