OK, so maybe this is a documented bug, but I've just found it the hard way, losing 17hrs of f***ing render time. If it is documented then I guess it serves me right for never reading any documentation! If you want to check it out, this is how... set up a simple scene in Bryce and light it with a light source. Set the light source to "gel" / "procedural" and then slap some outrageous colours on the light source texture. Click OK, etc. Render it and all works fine - the scene is lit with your colourful light. Now go back and un-check the "gel" option. Render the scene again (use superfine full render so you can catch what's happening) - but stop it say 75% of the way through. Save your scene. All fine so far, but... Load the scene up again and press "resume render". The render will resume, but it will have automatically checked the "gel" option on your light source, resulting in a stippled mess as it attempts to render the rest of the scene using different parameters! The only solution - unless someone knows different - is to either use a pure white gel for gel-less lights or render all your stuff in one go! Sigh. I hope this pic is worth it... >>>:[