Apparmor broken! How to fix?

[Gilles Gravier]

Hi!

Something strange happened on one of my Ubuntu machines. Now, during
boot, I get messages about apparmor configuration files broken... and
once the machine is booted, I can't log into it.

If I enter an incorrect password, I get the normal behavior (long prompt
and / or error message).

If I enter a correct password, I get an immediate permission denied
(SSH) or GNOME starts and dies immediately.

So I am wondering whether to simply remove apparmor or dpkg-reconfigure
it...

Question is... what package should I remove or dpkg-reconfigure?

I can boot in recovery mode, at which point I'm logged in as root.

In recovery mode, as root, if I "passwd USER" I get a segmentation
fault. But if I su - user, it works...

Ideas?

Thanks in advance,
Gilles.