Tried importing V4 from Poser 7 in Vue 6 xStream and after a while Vue died on me, they're probably still a few things to fix, probably on Vue side (Dual opteron dual core + 4 go memory, XP64)
But, Vue is still a pre release so .... :)

edit : created the exact same scene in poser 6, changed the setting in vue to use poser 6, exact same crash, so definitely not a P7 problem