I have found that once a file is corrupted it is difficult to get rid of the problem. I always make a "backup trail" by saving as "workfile1, workfile2" etc everytime I make a change to the file I don't want to have to redo. When I get a flaky file (any glitch that seems unusual ie a shader disappears etc)I back up in the trail to a "clean" file and start over. I have found that getting rid of unused master objects and shaders (Edit menu), giving objects and shaders real names, checking for inconsistancies in the object heirarchy, and in general keeping things organized seems to have an effect on file stability. Sometimes disabling Agrooves and grows for the file save helps. Sometimes I have been able to recover files by copying and pasting objects or shaders individually into new files. It all adds to the thrill of that final render! ;-) Ed