Before you get all crazy and do a system restore, do some best practice solutions and use some of the free built in diagnostics in windows.
First I would update the video card driver. Go to NVidia.com and get the correct driver for you computer and windows version.
If that doesn't help, run windows update and get any of the drivers windows update recommends. You don't have to do all the software updates, just the drivers.
If that does not help run CHKDSIK. Select automatically scan and repair bad sectors.
Then run memtest. Just type memory into the windows 7 or windows 8 search box.