If I understand correctly what you are saying, the stalks are intact.  If the stalks were breaking over, I would look at possibly K deficiencies and/ or some kind of stalk disease breaking the stalks down.  However, you seem to indicate that is not the case.

For roots, take a look closely at the roots - are you seeing insect damage on the roots?  You say this was a VT3, so hopefully that is controlling the corn rootworm insect.  However, look for possible insect feeding on the roots just to be sure.  Beyond that, if you are in a wet area this year, you might just have a shallow root system due to the wet year, and the wind just took it down.