It's not just P5. Pro Pack did that to me just two days ago. I had to stop the render. Reset the display mode, then resave the document, closed out Poser and then reopen Poser and the newly resaved document. It behaved itself then. Somehow in the crash during render it changed the display settings from Shaded Render to "Actual Render" and just kept trying to render the whole thing. Resetting your display like say, to wireframe and then back to the display setting of your choice should fix it if it's the same problem I incurred. Just be sure to resave the file with the reset Display Settings.