I saw frequent crashes using Carrara 1.0, but it's been stable in recent versions (1.1, e. g.) [Mac OS 9.0.4, 256 MB physical RAM, 400 MHz G3] I have found that I need to assign at least 200 MB RAM to Carrara 1.1 to avoid crashes. Not virtual memory. the assembly and model rooms make heavy use of the OpenGL extensions and your graphics card, so you could check those to see if they are up-to-date and if you have something active (like Toast extensions) that might conflict with them. The usual advice is to use a minimal extension set limited to quicktime, openGl, graphics card and related extensions. Haven't seen x-y transposition.