Adaptive Equipment problems of the 2018 Toyota RAV4

I had been using the adaptive cruise control at highway speed on the westbound CA 134 in glendale/burbank, CA. I had to merge into traffic from the hov lane disengaging the cruise control. I then used the auto transmission to shift to a lower gear to gain more torque in changing lanes when the car went into a stall and lost all power. Consequently we were rear-ended by another car. Our car went into a lockout and had to be pushed to the shoulder by the California highway patrol. I don't know if this was a random event or a glitch in the on-board computer. Or something else totally unrelated.