Choose and check the box for "Perform a clean installation" . This removes old driver conflicts.
Avoid third-party "driver updater" software, which often contains ads or malware. Use the official NVIDIA Driver Downloads page: : GeForce Product Series : GeForce 8 Series Product : GeForce 8600 GT (or your specific model) skachat draivera nvidia 8600
: If you see "Windows has stopped this device because it has reported problems," the driver might be too new for the card's physical health, or the card may be failing. Choose and check the box for "Perform a clean installation"