"mg" wrote in message
There are 6 or 8 spiral nails on our deck that will not stay down. The
boards are flat on the deck and do not appear to be cupped or warped.
But, within about 3 months of driving the nails down, they are back
up.

Aside from the suggestion to use ring shanked nails or deck screws, you
might also want to investigate why the nails are coming up. It *could* be
just because of general traffic, but it could also be because of especially
warped wood or the fact that it bounces escessively when walked on. Are the
supporting timbers all in good shape and reasonably flat on their edges?