So you have the VDC off but there are still nannies in operation
How hard are you pushing the car (is you experience level as a beginner, or some experieence in pushing a car).
My reason is that the residual stability control might be detecting sufficient yaw for it to trigger one rear brake to try and straighten you up (not ideal on a road course).
Check these threads
DIY Yaw Sensor rocker switch and
How to turn off vdc completely
Look at the bottom of page 2 of first post for explanation of trail braking - you will experience a similar feeling if you are close to the lateral grip or traction limit and the car senses wheelspin
Solution - install a switch in the power lead to the yaw sensor.