A friend of mine has almost the same issue.
AMD Phenom II X4 965
ATI GEFORCE 8500 GT
Corsair Dominator 8 Go (Kit 2x 4 Go) DDR3-SDRAM PC12800 CL9
Windows 7 64 bit SP1
Drivers / Firmwares
As recommended in most forums, drivers for graphic card are up to date.
Even motherboard firmware has been successfully flashed with last ASUS version.
Except for integrated DELL SMARTCARD READER in keyboard.
Hard freeze on any browser (Firefox, IE, Chrome - all up to date versions).
Seems to be always linked to FLASH PLAYER utilisation (pages using flash video content or flash modules)
Triggered by mouse scroll or mouse click.
Hard freeze, no BSOD, mouse and KB not responding, sound hashing for 2-3 seconds then silence. Hard reset needed.
Previously, exact same config (except HDD) ran with Windows 7-32 without any trouble during 1 year.
CHKDSK - no error
Withdraw 1 RAM unit, then other, switch them... no improvement.
Uninstall ADOBE FLASH PLAYER and use CHROME (with FLASH module integrated): it goes better but still freezing/crashing.
If someone got an idea...