Carrara 6 has a better way to handle textures. In the preferences Imaging, Scratch Disk.
Its a little confuse to use: you need to set the limit of physical memory will be used until Carrara use yuor HD as a virtual memory.
The better way is to use 10% of the value of yuor total memory:

If you have 1GB use 100Mb

Dont use low values like 10Mb because Carrara will use only 10 mb of your RAM to textures and you will end avery slow machine.

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