Tarmac is right on target, sometimes it just might be a poorly calibrated joystick (or one that is sloppy near the middle) or it could be that you are actually moving the controls all over like crazy. On the joystick calibration screen, re-calibrate, then look in the stick-position displays and move the stick around. You shouldn't see lots of spiking if you are moving it smoothly. You can increase the deadband if you want to remove small spikes from the stick (you may have noticed your autopilot kicking off which can be a symptom of stick spiking).
Stick stirring is the other option and is a style thing. Correct flying technique does not involve thrashing the stick all over the place, maneuvers tend to be more deliberate and forcefull but occur in a sequence. Just thrashing a stick around can be a successful defense but only because it abuses an inherent shortcoming in net-lag (which causes you to flip-flop around). Sure, you may succeed in a defense like this but the code realizes you are abusing the bug and locks your controls as penalty (which makes you dead meat). Not saying you are doing this, btw, just explaining the reasoning behind the reason it is the way it is.