My car has already stalled twice when driving. The first time, I was driving at a moderate speed and, suddenly, without any kind of explanation, it stalled. The steering wheel tightened and the brakes did not respond. I took it to the agengy, it was checked with computers and I was told no failure could be found. Everything was put back in its place and yesterday, the same event took place. Luckily this time, it stalled when being stopped. Can someone please help me?