I am reporting a serious safety issue with my vehicle, purchased from Ed Morse Cadillac. The vehicle has unexpectedly shut off while I was driving on multiple occasions (3 times to date). When this occurs, the entire infotainment and dashboard screen goes completely black, and most alarmingly, the brakes become unresponsive or extremely difficult to engage. This creates a highly dangerous situation where I am unable to control or stop the vehicle safely, putting myself and others at serious risk of a crash or injury. This is not a one-time occurrence—it has happened multiple times under normal driving conditions. I have contacted the dealership, but they have ignored my attempts to resolve the issue. This problem clearly involves critical vehicle systems and should be investigated as a potential defect. I am requesting that the NHTSA open an investigation into this issue, as this vehicle poses a danger to public safety.