Black ops - Freezing,Crashing,Fatal Errors

[EaZzY]

Hello, i have this problem for a long time. When i run the game i play ~ 1 map then i get fatal error or crash or freeze.
I tried :
1.Unistall the game from disc, update, verify game cache,start game ---> result Fatal error
2.Unistall the game, and downloading it from Steam, veify cache, start game ---> result Crash
3.Delete config.cfg after 1. and 2. --> result freeze and need to stop the game from Task Manager (Ctrl + Alt+Del)
4.Trying running the game as Administrator, under WinXP SP3, Disable display scaling on high DPI settings --> result freeze and need to stop the game from Task Manager
5.Tried modify,download config.cfg (multi gpu 0;multithreadevice 1) ---> result freeze and need to stop the game from Task Manager
6.Download CFG,CFG configorators etc. still nothing

My PC is :
Video: ATI Radeon HD 4850 512mb
RAM: 4GB
OS: Win 7 64x
CPU: Intel Quad Core Q9300+ 3.01 ghz (stock is 2.5ghz)
Motherboard Chipset: Intel Eaglelake P43
HDD:1TB Hitachi HDT721010SLA360 ATA Device (1000 GB, 7200 RPM, SATA-II)

Edit: I still don't have any solution send by Activision

Thanks in advance