After the recent kernel upgrade my old nvidia driver failed to load and X loads with a very low resolution and without detecting my second monitor. For my graphic card the nouveau driver is not an option. But I managed to fix the problems via removing current nvidia and nvidia-173. But probably you can just skip those commands and use the jockey-gtk as explained below.
sudo apt-get purge nvidia-current
sudo apt-get remove nvidia-173
sudo apt-get install –reinstall nvidia-173-updates
# now REBOOT!
Now it boots as normal with my second monitor but the nice configuration tool called ‘nvidia-settings’ did not work and says ‘The NVIDIA X driver on is not new enough to support the nvidia-settings Display Configuration page.’
Also my firefox 23 had performance problems for canvas rendering. I solved this via opening “about:config” and set layers.acceleration.force-enabled to true. I found this in the comments of this article.
Update: I was able to fix the all the issues just by switching to ‘(additional updates) (version 319-updates)’ when starting the tool called ‘jockey-gtk’! Afterwards also the tool xfce4-display-settings showed two monitors.