Im sorry i still dont have a "fix", but I may have found a way to highlight
the (many) problem polygons. I think it is possibly caused by import errors.

Open in WED, goto to faces mode, then select JUST ONE polygon, then keep
clicking on "select touching" button until no more selection is being added.
You will see this leaves a LOT of unselected polys.
This doesnt make sense, because if you hit "select connected" it will select
ALL the polys.
AND which polys end up not selected varies depending on where the start poly was too.
_ _
O.o