CST error simulation AMD64.exe

hello. when simulating my design always i got the s2 problems:
1. Render Engine Error: Matrix calculation crashed while executing multiple threads. Caught unhandled exception (check for race conditions). Error in calculating solver matrix.
2. HD_SOlver AMD64.exe error
what happened?
Here is my notebook LENOVO Z570 conf:
CPU Name: Intel(R) Core(TM) i3-2130 CPU @ 2.130GHz
Memory information: 4GB RAM
NVIDIA? Geforce? GT540M 2GB graphics
OS information: Microsoft Windows 7 Home Premium 64 Bit version

thanks for your cooperation