Thanks, Shonner.  The splash screen shows 5.1 but I've downloaded the patch anyway.  It was probably my fault using Save, instead of Save As, and renaming the render.  I'll render to a new window and use Save As from now.

BTW you have some gorgeous renders on your site.  Those and a search through the Carrara gallery gave me the incentive to rush down to the newsagents and pick up a copy of 3DWorld.