Posers selection of body parts via mouse is terribly wonky (It always has been) not to mention lag is the worst of any 3d app I've ever used (regardless of how powerful your computer is or the relative complexity of the scene your working on, although these things contribute). For anything other than posing I try to use the heirarchy, which I always keep open, for selection. Strong emphasis on the word try. I personally have become so used to these annoyances that I hardly even notice anymore, I suspect this is the case with most who've used Poser for a while. Have you tried using bounding box preview to see if there's any difference? Although I don't think this would be an acceptable solution. Anyway, I'm able to select body parts via mouse through obscuring body parts in my Poser, so...