Do you have multiple versions of Poser installed? 

Also make sure that you install everything you are trying to import within the Runtime folder of Poser 6, as Vue may be trying to locate geometries etc in Poser Runtime that are actually in the DAZ Runtime.

I know that Poser 7 and Vue Infinite (which I use) do not always see eye to eys on paths and so on, esp if a pz3 file has been opened with different versions of Poser.

Apart from that I don't know what else to suggest.