i would clean install your drivers incase its a problem with them, download driver fusion and the latest nvidia drivers.
uninstall current driver and dont restart.
run driver fusion nvidia driver cleaner and restart.
install nvidia driver.
also what antivirus are you using, if its avast i would remove it as it can cause random system performance and other problems.
commodo internet security and AVG are good alternatives.
i would also get ccleaner and run the file cleaner then the registry cleaner multiple times till it finds no more errors, do this after reinstalling the drivers and removing avast if you use it.