I had the same problem :my computer was often lock up with Poser.It was about my memory ram.Check with memtest if it is ok:sometime i had write errors on one of my DDR memory.I change it for new one and my probleme was fixed.Or Check if you are enough memory for the scene you are create(too more peoples and props..)...Poser is not the best soft for manage memory.Now with 2 meg DDR ok i have no more freeze with Poser