Rear end chattering

Hi. I'm a new SVX owner - my wife and I really love the car. Of course all things that seem perfect seldom are - which brings me to my question. Recently the rear end started chattering after the car warms up some (about three or four minutes on a cold Wisconsin day) but only when simultaneously accelerating and turning. Straight line driving is fine. I unplugged the "front wheel drive fuse" to disable the rear wheel drive and the chattering is completely gone. I've been driving with it like that ever since. Of course, with Wisconsin winters it would be nice to have AWD. Any ideas? Thanks!