Windows 7 64 bit NVIDIA driver install error "Stereo Server has not been properly installed"

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Noted a number of users with the same error. "Stereo server has not been properly installed"
I'm running 64 bit Win 7 build 7600, with NVIDIA GeForce 9800 GX2 graphics cards - tried to install the NVIDIA 64 bit drivers - version 191.07 and get the BSOD. Tried to safe uninstall and reinstall with the same result. Now using Win7 native drivers - but...

Does anyone know of a fix?

thanks in advance