Hey, maybe it is the long lost and time-forgotten, but all so mighty spirit of Don Quixote. (cue the machine laughter sound effect)
http://en.wikipedia.org/wiki/Don_Quixote
Or maybe, it was a magnetic disturbance, from me belt buckle rubbing against me wool cardigan.
Well, jokes asides, folks you just cannot build structures nowadays without something crashing into it. I am convinced that nothing off-world or anything exotic impacted with that windmill in England.
Now as for the one in Aurora Texas, despite the strange metal content in the ground, the alledged claim that the property owner hid the debris thinking it was valuable metal, the sworn affadavits of first responders on the scene, and the story of a secret burial ceremony in that cemetary to bury the "alien occupants", I still have my doubts, but I am open to suggestions if anyone can show beyond reasonable doubt and with scientific collaborating computations and formulae, that the impacting object was not earthly in design or origin if not man-made at all. I am sure in both of these occurrences the investigators are missing some obvious and simple explanation.