The incidents is summarised on the BBC website
Canadian Grandprix on 8 May 2008. The safety car had been sent on the the circuit following a crash. Several cars used this as an opportunity to get new tyres and fill with fuel by going to the pits. When going to rejoin the race Hamilton crashed into the back of Kimi Raikkonen who was stopped at a red light. Both cars were too badly damaged to continue.
Hamilton clearly made an error. He didn't see the red light and didn't realise the cars in front had stopped until it was too late. But my question is why did he make the error.
I noticed on the TV highlights that a car also went into the back of Hamilton, showing others made the same mistake. This leads me to wonder whether the lights are located correctly. The drivers in front can see them but people behind can't. Clearly Hamilton did not crash on purpose as he was having a great race. The crash allowed Kubica to win and take Hamilton's spot as number 1 in the rankings.
Of course Hamilton is punished and everyone says he is stupid. No ones asks why two people made such a fundamental error, so it will happen again.