This is something that happens occasionaly and I could never figure it out. I'll close down a file that is perfectly good, but when I re-open it, it's there but there is nothing on the screen. All that I see changed is that the light control in the upper left corner is black and even when I create new lights, there is still nothing on screen. Is this a corrupt file that somehow still opens but loses its props, characters, backgrounds, etc. or is there a fix to this. Thanks for any help.

I have seen this happen, but very rarely. In the cases where it happened to me, it was a corrupted file.

 PERHAPS it stops writing to the file too soon? If you've closed down Poser before the PZ3 was fully written? Or if you're using an external hard drive and that one isn't plugged in? Poser still references stuff in the PZ3.

I'm guessing wildly here, luckily I have never seen it happen myself.