The Null.obj sounds like there's a character file that doesn't properly name its object file, or an obj file that can't be found where it's supposed to be. 

Could there be a reference to an external runtime that isn't
actually present, or which has moved?  P7 seems to be more
fussy (or buggy)  about the runtime list. 

As an experiment, you might look at the libraryPrefs.xml file,
which will be in your Documents and Settings folder under Poser 7.

Here's what mine looks like; the fourth line shows that the P6 runtime
(index 2) is the one that I actually used.

You could try changing the circled number in the fourth line to the index of the
"home" runtime ...  which is probably zero but you should check anyway....

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