My Xubuntu system seems to start just fine: It leaves my at the login screen. When I log in the normal desktop appears.
However, when I press CTRL+ALT+F1 (to F7) I am sent back to a new login screen. My old session seems to be lost (I do not know how to get back). Also when I want to lock the screen I am send back to the login screen. Again, when I enter the password a new session is started, the old one is lost.
I am puzzled as I could not find any report about a similar problem. What could be wrong?