My system is: Athlon XP 2700 NVIDIA GPU GeForce4 Ti 4200 (with NVIDIA driver version 1.0-9631) Debian Etch
Last system modification was an update of the debian system with the availabe patches on 05.01.2007. This is most probably the root of the problem.
Isn't there a "sister" package repository somewhere that would have the NVidia drivers that install in a package-controlled way, and update automatically with the rest of stuff?
Livna provides that for RedHat/Fedora distros and it solved it for me (not having to reinstall drivers after every update).
Cheers, KUba