  It is known that weak coupling calculations of absorption or emission by
slightly non-extremal D-brane configurations are in exact agreement with
semiclassical results for the black holes they describe at strong couplings. We
investigate one open string loop corrections to processes involving single and
parallel D-branes and show that a class of relevant terms vanish, indicating
that these processes are not renormalized. Our results have implications for
five dimensional black holes and extremal 3-branes.
