I have the same problem. I just got a new and faster computer and it still does it. Changing the paging file and defragging does nothing. My page file is on a different partition than Poser 4. And Curious Lab's update for computers with more than 1GB memory doesn't do anything either. I think Poser 4 just hates fast computers.

Poser 2, 3, 4, 5, 6, 7, 8, 9, 10, Pro 2014, 11, 11 Pro