Radeon x850 Crashing

Hi
I have a Radeon x850 card that crashes after 10 mins or so of "heavy" use (eg BF2, or video testing). ATI support not great.

Any help appreciated...thank you


System Specs:
Board: ASUSTek Computer INC. A8V-E DELUXE 1.XX
BIOS: Phoenix Technologies, LTD ASUS A8V-E DELUXE ACPI BIOS Revision 1009 10/24/2005
2.20 gigahertz AMD Athlon 64
1024 Megabytes Installed Memory - Corsair
RADEON X850 Series


Graphics software:
Driver Packaging Version 8.09-041221m-020455C-ATI
CATALYST™ Version 05.1
Provider ATI Technologies Inc.
2D Driver Version 6.14.10.6505
2D Driver File Path System\CurrentControlSet\Control\Video\{2ED0683D-772C-4650-8B49-7AC9B2AD97AC}\0000
Direct3D Version 6.14.10.0283
OpenGL Version 6.14.10.4830
CATALYST™ Control Center Version 1.1.1816.25974

ATI WDM Rage Theater Video NSP
ATI WDM Specialized MVD Codec
Bluetooth Audio
KWorld DVBT 2388x AVStream Crossbar
KWorld DVBT 2388x Transport Stream Capture
KWorld DVBT 2388x Video Capture
KWorld DVBT BDA Tuner/Demod
MPU-401 Compatible MIDI Device
Realtek AC'97 Audio for VIA (R) Audio Controller
Standard Game Port