Cruise Control problems of the 2014 Toyota Prius

Acceleration driving east on us rte. 50 at about 60 mph: vehicle accelerated for no apparent reason. I nearly ran into the car ahead of me. This car is equipped with radar adaptive cruise control, which was engaged at the time. I turned off the cruise control in time to avoid a collision. Unintended acceleration has sporadically occurred, but it is usually fairly mild. This time it was so powerful that it felt like I had stomped on the accelerator; the engine roared and the car took off at full throttle. Thankfully I was traveling at the max distance of the cruise control. Acceleration was not caused by floor mats. I watched while the dealer service manager checked. Deceleration driving east on I-the car ahead of me signaled to exit the interstate and turned smoothly onto the exit ramp. As soon as he was out of my lane my car's cruise control locked on to the that of the exiting car and vigorously applied the brakes. Stepping on the accelerator did no good.