I've been working on trying to discover if there are any bugs with Poser 8 and it seems that Poser 8 doesn't create preview thumbnails for older content.  I installed Aiko3 and some older Daz content and some older content that I purchased on Renderosity and the only thumbnail that I got was a guy holding his hands out showing that there was no thumbnail image.  The only thing that I could think is that poser wasn't reading the older content correctly.

Let me konw if you are having a similar problem with missing thumbnail previews and if the missing thumbnails is from really old content

Frederick
Poser By Design