Thats a unpleasant feeling isn't it. That happened to me on our OutBack S3 this year. Headed straight into a spot that didn't look wet but was, started spinning and digging a bit of a hole, and the steering wheel was spinning like a roulette wheel. Had to reach down and turn off the autosteer control box. Turns out that the sensor that picks up the rotation of the steering column had come out of adjustment. About a 2 minute fix.
Hopefully its something simple like this on yours. I have no Idea how the Intelisteer system works, so this may or may not be of any help.