Poser will always ask about missing files when you load a PZ3, but I had it ask at render time just a couple of days ago.

I had changed a material, but had used an older file by mistake.  It loaded fine, but asked for a deleted image on rendering.  It was a node mask I had decided not to use, so it seems Poser doesn't actually check to see if the images are there when you load a mat in the mareials room.

That's the only time it gave that message when rendering.

John