Attached Link: http://www.microsoft.com/technet/sysinternals/utilities/pagedefrag.mspx

Have you changed anything recently? Installed more memory, changed hardware, that sort of thing? Poser is sensitive to issues with memory and virtual memory, P4 (it seems) especially so. My installation motored along fine for ages then suddenly started giving out of memory errors on rendering. Assuming you're using an Windows NT-based operating system (2000 or XP) the first thing you might try is defragmenting your system files, in particular the paging file, using pagedefrag from the link.