After a recent update to Ubuntu 12.04, my Dell Latitude D620 Laptop quit mirroring the display across the laptop screen and the television connected to the dock’s S-Video port. I had previously chosen not to upgrade to Ubuntu 12.10 because of this issue, and 12.04 had worked correctly until today. It seems that the driver installed quit supporting some of the options I needed:
root@ishta:~# nvidia-xconfig --twinview nvidia-xconfig: unrecognized option: "--twinview" Invalid commandline, please run `nvidia-xconfig --help` for usage information.
It appears that installing an older version of the NVIDIA drivers:
aptitude install nvidia-173
and removing the current version of the drivers:
aptitude purge nvidia-current
solves the problem. Hopefully this will work for future versions of Ubuntu as well.