Nvidia graphics problems

I use an Nvidia GeForce 630 video card with OpenSuse 13.1. Using the 31.1 package the software installs without problem and basic functionality works. However, seemingly randomly, screen update behaves oddly. Parts of the screen are continuously redrawn until focus moves elsewhere or parts of the screen are redrawn incorrectly. This doesn't happen all the time, but is especially evident with apps that draw complicated presentations, e.g. web browser.

Any suggestions about what might be the problem would be greatly appreciated.

Thanks,

J. Morris