You can try doing a clean install of your video drivers by first downloading the driver and saving somewhere. Download driver cleaner pro from
here and install it.
Then go to your Control Panel>System>Advanced System Settings>Hardware>Windows Update Driver Settings and choose Ask me each time when I connect a new device. This step is to stop Windows from installing its own driver for your video card once you uninstall it.
Now once you've done all of that, uninstall the video driver and reboot into safe mode.
In safe mode, it may ask you to install a driver for your card, just cancel it. Run Driver Cleaner Pro, and in the drop down select nvidia WDM and click start. Then select nvidia and click start ((note: it may not happen to you but when i clean with the 'nvidia' filter, it cleans the registry like it's supposed to but then doesn't stop. I've had to bring up the task manager and kill the process)).
So you've uninstalled the video driver, and cleaned the registry of leftover driver entries. Reboot again into normal Windows. Cancel when it asks to install the driver for your card. and finally install the driver you had downloaded previously.
With these steps, you've ensured a clean install of your video driver. Hopefully it may help some of you with your game problems as I also have the 175.16 and haven't had any problems with any Source games (CS:S, HL2 & EP1 & EP2, TF2, HL:S, etc...), CoD4, Guild Wars, Halo, UT3, DiRT, Bioshock, Crysis,...