Newer ATI cards will exhibit this behavior if they're not getting enough juice or if the power supply's +3.3V dips too low.
If your motherboard/PC manufacturer provides hardware monitoring software, use it to determine the stability of your power supply. Everest (http://www.lavalys.com/products/overview.php?pid=3&lang=en) can display the hardware sensor info for most motherboards.
I just recieved my Sapphire x1800gto today and installed catalyst 6.4, restarted, then loaded call of duty 2 after about two minutes of playing multiplayer, vpu recover came up and forced me to shutdown call of duty. Sometimes I will be at the menu to start a server and it will vpu recover. Tried on other games, same problem.
I have tried the following drivers, uninstalling the old one first:
Catalyst 6.4 Beta X1800GTO Crossfire
Remember that this is a fresh installation of windows and call of duty. It will never VPU recover when I am using an application or on the desktop, only 3D games.
I have sent numerous error reports to ATI.
Athlon 64 X2 3800+ @ 2.25GHz
2GB Corsair XMS Memory
250GB Seagate SATA1