You say there's no way to update to the latest Nvidia Display drive in Device Manager. Why is this?
Download and unzip the driver and either Run it, or browse to its Driver file from Device Manager>Display driver>Driver>update>Browse until it picks up the driver.
If there's further instability I would run the Repair Install as a last resort before clean reinstalling to wiped HD. A Repair Install is an in-place Upgrade which keeps everything in place while reinstalling only the OS, as explained in the tutorial I linked. You only have to reactivate at Computer>Properties.