I am using debian testing for a while .. a few weeks ago after updating and upgrading i had the problem that the nvidia driver install script was run successfully .. but i couldn't start X anyway.. not possible to load driver nvidia.
somehow some xorg-modules are now in a different directory.
so you maybe have to advice the nvidia driver install script where to find the right modules.
this worked on my machine:
sh NVIDIA-Linux-x86-1.0-8762-pkg1.run --x-module-path=/usr/lib/xorg/modules
i hope this helps someone ..
I only have one Computer ... so it took me some time googlin' around (with links2 or lynx) to find that simple solution.