This also happened to me on an upgrade from Oneiric to Precise Alpha2. I switched to GDM to get my system working at the time.
Purging lightdm did not work, as the originally reported, I had to manually delete the files in /var/lib/lightdm.
This also happened to me on an upgrade from Oneiric to Precise Alpha2. I switched to GDM to get my system working at the time.
Purging lightdm did not work, as the originally reported, I had to manually delete the files in /var/lib/lightdm.