Your antivirus may be blocking certain files. You can also try downloading the driver from nVidia's website.
You'll also want to be sure to uninstall/install the new driver properly:
1) After you uninstall from the "Device Manager", sometime it will ask for you to reboot in order to complete the un-installation. Whether it prompted or not "DO NOT REBOOT" instead just cancel it. Now, go to STEP#2.
2) Go into your GPU driver folder (Usually by default at C:\Program files\ATI or Nvidia) and delete the folder. Now reboot, and when window loads up and a new "Hardware Found" just cancel it. Goto STEP#3.
3) Now, install the new drivers and follow the on-screen and than reboot when finish. When window loads up it should automatic load the new driver. But if not than you have to manually point it to the new GPU driver folder and it should load from there. If all fails than go to STEP#4.
4) This maybe your last resort if STEP#1-3 fails. But 80-90% of the time STEP#1-3 should take care of any problem.
If not than you need to repeat STEP#1-2 and got into your "REGEDIT" and clean out any left over junk, before you can do STEP#3. CAUTIONS: "I DO NOT" recommend this step unless your totally confident and know exactly what your doing. It can really mess up your system and could end up re-installing windows. Good Luck!
