I am writing to report a serious safety concern regarding the adaptive cruise control and rear cross-traffic alert systems in my Chevrolet Blazer. These systems are malfunctioning in unpredictable and potentially dangerous ways. On multiple occasions while driving on the expressway, the adaptive cruise control has abruptly and forcefully applied the brakes without any apparent reason. There have been no vehicles directly in front of me posing an immediate threat. While there may be traffic in adjacent lanes, my lane has been clear. This sudden deceleration is alarming and dangerous, creating a significant risk of rear-end collisions from vehicles following too closely. The red lights will come on and indicate an imminent problem but it is a malfunction. The abrupt stops are frightening for all passengers, and the frequency of this occurrence is troubling though on rare occasions since I have first owned the car. I have observed similar complaints from other Blazer owners on online forums, reinforcing my concern that this is not an isolated incident. The dealer has not being able to reproduce but acknowledges that other drivers have a similar issue. Further compounding this issue is the malfunctioning rear cross-traffic alert system. While backing up at low speeds, the system will unexpectedly and forcefully engage the brakes, even when there are no vehicles present in the surrounding area. While less dangerous than the expressway issue, this erratic behavior still indicates a significant system flaw. I understand that adaptive cruise control and rear cross-traffic alert are intended as safety features, but their current malfunctioning poses a substantial safety risk. I urge you to investigate this matter thoroughly. I expect these features to function correctly and reliably. I request immediate action to address these defects and ensure the safety of myself and other drivers.