Adaptive Equipment problems of the 2014 Toyota Avalon

Driving down road. . No cars in front of me no objects in road. Clear sunny day when the pre-collision system alarm sounded and the pcs indicator light lite. The abs engaged. And the car came to a complete and sudden halt. Luckily noone was behind me, because if there was, a rear end collision could have occured. This issue did occur to a lessor extent on two prior occasions (about 1 month ago) but the car did not come to a complete halt as it did on 7/6. In both of those instances, there were no cars in front of me and no obstructions in the road. The road(s) were strait. No curves. Took car to Toyota and they refuse to do anything about the issue because they could not duplicate the problem. Im afraid that this will happen again, which could hurt myself, others or cause property damage.