Comment 55 for bug 78282

The return to the login prompt is because Feisty changed the default to not allow multiple logins for the same user. If you are running Xubuntu, for example, go to Applications -> Settings -> Login Window and there is an option on the General tab to disable multiple logins for a single user. By default this is now checked, which prevents you loggning in on :1 when you are already logged in with the same user on :0.

Regards

Warren
http://grumpymole.blogspot.com