Are they showing up while you are working in Poser? I just wonder if they are like MS Word's temp file, which opens when you are using a file in Word. But, like I said, the only time I've noticed these pzSav_blah.pz3's is when, for some reason or another, Poser didn't finish doing something. Sometimes it opens and is a perfect copy of whatever I was working on and sometimes it is a single light, black and off, with nothing in the pic. If you don't need it (ie, it's not the instance when it just crashed and actually saved your work), delete it.