Bug#241096: same here, and more..

[francesco fantoni]

i have the same problem: session menu messed up, with just "default" and
two failsafe sessions.
trying to login with Default, leads to a message stating that " last
session lasted less than 10 seconds" and the going to login gdm screen
again.
i can login to a gnome failsafe session, that seems to work fine
(altough i don't exactly know what failsafe means in this case), but
nothing else.
quite weird indeed, don't know hot to fix it.