http://www.youtube.com/watch?v=e0xVHPiKRec

 

That's odd. It just folded in half. The nose wanted to stay down, but somewhere in the middle it gave way.

 

My guess: Too much rear downforce and engine vibration over too many runs lead to metal fatigue in the front chassis somewhere. A weld broke, and that was the final straw.

 

If I remember right the flex in the middle from the front wing and that big rear one actually help it keep traction.. when every bit of it counts. I forget the deflection the middle sees mid run, but it could cause that if anything let go in the middle like Stocker said. One weld not holding it together could cause a major failure.