The only time I've ever experienced anything like what has been mentioned is when I didn't recover correctly from a stall. Or rather, when I thought I had, but I hadn't actually recovered yet. It has happened a few times, usually when I hadn't been playing a while...
I'd push the envelope a little to far, and my 190 would get really jittery, and the right wing would drop (i.e accelerated stall). So, I'd counteract the drop with a little rudder, push the nose down, and consider myself "recovered". Only problem was, even though it was stable, the next move I made of any kind would make the LEFT wing drop... it was wierd. I would go back and forth dropping the wings alternately. I never do manage to recover when that happens, I always plow into the ground.
I couldn't tell you exactly how it happens, I only ever got it in the 190 and 109. But then, I flew those two planes for the vast majority of my AH career, and I pushed them harder than I pushed any other plane.
I don't know what causes it, I don't know if it is even close to what other people have experienced... for me I think it was just an issue of being to hamhanded while trying to horse a plane that wasn't really designed for slow-speed knife-fighting into one.
