Comment 25 for bug 188787

This is a bug in how I suggested to test the patch. I am very sorry for that. Explanation: to reconfigure the xserver one should not run dexconf directly but rather

dpkg-reconfigure -phigh xserver-xorg

which answers something like:

xserver-xorg postinst warning: overwriting possibly-customised configuration
   file; backup in /etc/X11/xorg.conf.20080424203010

So the proper way to test is to rename old /usr/bin/dexconf to something else, substitute it with new version, chmod 755 it, and then run "dpkg-reconfigure -phigh xserver-xorg". This will properly backup existing xorg.conf. In any case dexconf should have configured X correctly as it did the first time you installed ubuntu. I don't own an nvidia card (or better I own it but i never reconfigured *that* machine :)) so I don't know why this happened. Perhaps you just had to reconfigure also the package containing the nvidia driver after running dexconf.