nVidia driver issue

I have started to see patches of blue/green lines areas on pictures, games, and dvd's. It seems to affect areas where changes in lighting occur or shaded areas. I first noticed this after installing updated drivers for my network card. So, I installed nVidias' latest drivers - 93.71. It fixed the problem for a little while then it came back. Now the problem occurs right from startup and affects any picture/game/dvd i play. It seems to hang around shaded areas. On one occasion the computer sort of stalled, the graphics went all wierd and it stated "nvidia driver failure". I would greatly appreciate any input on this matter.