You need to provide system and project information or this is going nowhere. This could be anything from a flakey graphics driver to something you do in your project.
Thanks for reply,
System Info as follows: Intel i7-920 Processor
Asus P6-T Deluxe MB
24 GB Ram
Nvidia GTX 470 Video card (driver version 301.42)
Hope that is what you need.
As far as the project, it is a HD 1920x1080 29.97 15 second ad. Not sue what else you want to know.
Have you updated the graphics driver? That raytrace stuff is hyper-sensitive to any wrong driver/ bad configuration...
Yes, that is the most current driver as far as I know.