Why CityEngine closes automatically?

GucluSen

I installed 2012.1 version CityEngine software but when I work with the program, it suddenly closes.
Sometimes, this situation is being during different operations.

For example;
I want to study Tutorial 1.
I create a new project and a new scene but when I want to try copy-paste "assets" and "rules" files, the program closed itself.
I don't understand, how can I solve this problem?

Thanks,

My System;

Intel Core i5 CPU 2.27GHz
4GB RAM
64 Bit Windows 7 OS

GucluSen

My graphic card is ATI,
I have read the post about problems with ATI;

Since deactivating the Texture Compression will be problematic with datasets that contain many textures, we recommend to deactivate the MipMaps since it only results in a very marginal flickering of the textures in the viewport.

I have tried to do this tips and disabled "MipMaps" or disabled "Texture Compression" but there is no difference.

When I've selected a rule in the navigator window, CityEngine has closed. Sometimes, I've selected a rule and created several buildings. Then, I want to select a different rule file, CityEngine has closed again.

I am going to try to increase RAM or I will try to install CityEngine another computer that has 6GB or 8GB RAM.

Thanks,