Well we still don't have a real explanation, Slowpoke, you can't leave us hanging so long, some of us have nothing better to do than worry about h2's all day.
Having leant a better part of today to this conundrum I hypothesize: Slowpoke drove up unto the rock hidden in the grass. Some how he managed to get the drive shaft resting on top of the rock and thus most of the H2's weight was resting on the drive shaft and the small contact point made on the rock. Shaft then bends on rock and a little gas is enough to snap the deformed shaft.
How's that sound.