Cannot start X server after upgrade from Oneiric Ocelot to Precise Pangolin
I am running Kubuntu.
I just upgraded from Oneiric Ocelot to Precise Pangolin, and apparently everything went well.
But when i tried to login in the graphical window, I got the following error message:
"WARNING: Cannot open ConsoleKit session: unable to open session: the permission of the setuid helper is not correct".
After that, i get back the login screen.
If I shut down the Xserver and log in the system by console, the login goes well and I can navigate directories and do things (the few I can do by shell...), so I definitely think the problem is with the Xserver.
If it can help, I add that I have Nvidia graphic card running with the proprietary driver. The only other proprietary driver that I have in the system is for the Samsung printer. Everything else is standard Kubuntu.
I could obviously renounce the upgrade and make a clean install, but if it is possible, I would like to avoid that.
Any help is appreciated.