The card probably isn't causing any problems, since Poser doesn't make use of hardware acceleration. But stranger things have happened, so I won't rule it out entirely. Check your fans and heatsinks; be certain everything is mounted and running properly, and that your case has unobstructed airflow. Poser makes a pretty good stress test ... I haven't seen many applications that can heat up a CPU faster. When I upgraded to an Athlon processor I had all manner of problems that only appeared when I ran Poser, and it turned out to be a heat issue caused by an improperly-mounted heatsink. Luckily, my new motherboard had failsafes to power-down the system in such a situation, so no damage was done.