Ok, your hardware seems like more than enough :) Another thing to do is to visit CL's webside and grab the memory updater. The out of memory bug is very common in case of people using more than 1 Gig of virtual memory. This concerns both P4 and P6. If you are using WinXP/2000 try to max your v.m. to 4095 megs. If this does not work, the only (lame) way I can think of is to reboot a computer and reload the scene.

Sounds like a bit of hard work for your hardware. In case of poser4 pro, specially when rendering complex scenes some textures just happen to disapear (object is rendered properly, but untextured) They probably are not cached correctly or not cached at all. Let's hope CL will debug their latest project with SR (comming soon). Using poser4, try increasing the amount of virtual memory and free some space on HDD. Hope that helped a bit :)

If they do it in a proper way- i mean not jamming the whole memory- with all my heart YES. History data should be cached on HDD IMHO- Otherwise forget it :)