2000 C230 - 84,000 miles. What is happening when I'm driving along and I feel like I just ran over something, the steering wheel lurches, and the BAS/ESP light comes on with the triangle explanation point light. I stop, turn off the engine and all the lights are off and all is well. This has happened 4 times over around 15000 miles. Once at high speed after a hard brake, and once backing up, and then twice just at around 40-50 mph for no apparent reason, except being in heavy start/stop traffic. Any ideas?