You need the Poser Pro Pack Memory Updater - "For Poser Pro Pack users with greater than 1GB of total memory (RAM + virtual memory = more than 1 GB.) to run normally." - from Curious Labs' download page. Poser 4 users need the 4.03 update. There is no fix for Poser 3 - other than throwing away RAM until you have <= 1GB. :(