Every since I purchased the vehicle, when the temperature is over 88 degrees in the summer and the vehicle has sat in my work parking lot, when I leave work at 5 PM and start the vehicle the VSA light and warning light come on with a minute of the first movement of the vehicle. When the light comes on there is a loud clunk noise and the brake and steering for a fraction of a second locks. One time it happened when I was in a turn and almost hit a wall. This is an ongoing problem every summer when the temperature is high. I have to drive home with the lights on and that is a 35 mile commute. The dealer had the car for three days and could not simulate the conditions and could not find any thing wrong. I have tried to get to the dealership when the light is on but by the time I leave work and drive to the dealer their service department is closed. I have asked to have a district service manager and/or the service manager at the dealer but so far I have heard from no one. I am concered that the vehicle stabitalization system is not safe if I had to make an emergency turn and that the vehicle would roll.