Yeah, same here.  I lost a huge scene I was working on because I forgot Poser 7 came with use external binary morph targets on by default.  I turned it off in Poser 6 when this happened and never used pbm again because its just too iffy!  Same goes for saving a Pz3 as a Pzz, had those get corrupted on me as well.  

As you already discovered if you get rid of the pbm link when Poser asked to look for it and you tell it no, the file will open but with no morphs.  In Poser 6 I could salvage this somewhat because I could open the animation Pallet and copy and past the contents into a text editor.  Once I had done that, and turned pbm off, I could reload (swap) the no morph figures out of my scene replacing them with new morphs intact from the library.  I then could copy and paste the settings back into the animation pallet and restore my scene. 

Notice I said used to.  That's cause appararently Poser 7 you can't copy and paste from the animation pallete like that any more.  So that totally sucks as I made use of that little trick quite a lot!   So, for now, I am trying to salvage the current scene I just lost by going back into Poser 6 and doing there. 

Having said all that.  I still like Poser 7 overall.