I have the exact same issue as already reported by Janus, but i'm on Win7 64bit.
I have dug a bit into this and it looks like
SDL.dll and
SDLhack.dll are the same file in r09. If i understand the PyLNP internals correctly it copies the dlls around when you hit the enable/disable buttons, at least that is what seems to happen in older versions of the pack. So i guess one of those files should be the
.dll provided by an un-hacked dwarf-fortress and the other one should be the hacked version?
Fun fact: in r08 i can't disable the hack, but have not noticed so far since i don't really want to do so
.