Comment 5 for bug 303458

zedtux:
OK, then we can try to cleanup by hand:
$ sudo rm -rf /var/lib/samba
$ sudo mkdir /var/lib/samba

pam_smbpass.so is known to segfault if the /var/lib/samba directory doesn't exist, or if it is non-empty, filled by something it doesn't like. I never saw it segfault when using an existing, but empty /var/lib/samba... yet :)

(As I said in comment 3, to clean up, you should have purged *both* samba-common and libpam-smbpass, ensure that /var/lib/samba has been removed, and then reinstall libpam-smbpass (which will reinstall samba-common in the process). That's because the /var/lib/samba directory is installed by the samba-common package, not the libpam-smbpass one.)