If you experienced problems with the NVIDIA driver 173.14.09 you might want to give version 173.14.12 a try.
The driver is available on Hardy in the hardy-proposed repository (you will have to install it through EnvyNG, if you haven’t already done so) and should now work with Xen kernels too (thanks to a little trick which I backported from Intrepid).
The name of the package for Intrepid is nvidia-glx-173.
Added support for GeForce 8600 GS.
Fixed a problem with missing rendering in OpenGL Workstation Overlays.
Fixed a problem with running some SDL applications and virtual terminal switching.
Fixed a potential crash in nvidia-settings when saving to the X configuration file.
Improved error recovery paths in the case of corruption of the commands sent to the GPU.
Please test the driver (for Hardy) and report your experience with the driver in this bugreport.
NOTE: the driver has been uploaded today but should be available tomorrow.