I've seen that bug many times. Restart (after turning on Virtual Memory to physical RAM + 1). Then go to "About this computer" and see how much free RAM is available. Set Carrara 10 MB less than the free RAM, then restart. It might run after that, but I really think you need at least 200 MB (256 MB physical RAM). Turn off virus-software, TurboMem, RAM Doubler etc. Run with minimum extension set (Quicktime and CD-ROM).