Yamaha Grizzly 2

I have a friend who had the same thing happen. She has a 2005 Yamaha Grizzly 660 and while she was just putting along, it accelerated on it's own, pitching her over the edge of a canyon. She was badly hurt, airlifted to hospital. I'm checking to see if anyone else has had this problem. Would like to contact lookinfortrouble about it.