game crashes on turn 477-478

[bigguy24]

as soon as i end my turn at the end of 477 the game crashes with no messages except the microsoft one. could it be my game card. here is my sys
System Information
------------------
Time of this report: 12/15/2010, 21:58:52
Machine name:
Operating System: Windows Vista™ Home Premium (6.0, Build 6002) Service Pack 2 (6002.vistasp2_gdr.100608-0458)
System Manufacturer: Acer
System Model: Aspire M5201
BIOS: Default System BIOS
Processor: AMD Phenom(tm) 9500 Quad-Core Processor (4 CPUs), ~2.2GHz
Memory: 8190MB RAM
Page File: 2255MB used, 14341MB available
DirectX Version: DirectX 11
DxDiag Version: 7.00.6002.18107 64bit Unicode

NVIDIA GeForce 9500 GT

any idea's?

[QuantumTarantino]

Top 5 sections of DXDIAG please.

On the turn of the crash, are you moving across the map?
Do you have helicopters?