You don't mention what version of Poser you're using. Have you visited the Creative Labs site and downloaded/installed all the updates for your version? Poser out-of-the-box does have numerous "issues", but with the updates available, most users here have reported P4, PPP (P4+ProPak), and P5 to be pretty stable on a stable machine. Graphics programs as a whole are pretty resource-intensive, and a lower-powered or unstable computer can suffer a bit under the load.