Driver update causes DVD playback to Blue Screen

I am new to this forum
When trying to update to an Nvidia video driver with Cuda support I get a blue screen when using any video playback software, the Cuda development environment works but video playback causes a blue screen where missing driver nv4_disp.dll is displayed.
I am using a Geforce 8600 GT graphics card and a Geforce 6100SM-M mother board. Any help would be much appreciated.