I had that ground plane thing happen in C2, but haven't run across it yet in C3.... I managed to get rid of it by grouping everything (after all the camera moves were set and everything) and moving the entire group a couple inches above zero Z. Maybe I was deluding myself into thinking that it really fixed the problem, but the vanishing groundplane problem did cease when I'd do that. I'd be interested in hearing what it is that you're using your animations for. If it's for acutal broadcast over airwaves, there are a few things that Carrara does that might cause problems. You can fix these problems in Premiere Pro (maybe in earlier editions -- I can check). But if it's for a computer based or cable based broadcast, it's probably not necessary to worry about them.