PAM dlerror: after disk-upgrade from debian3.1 --> to 4.0

This entries I find in the auth.log and it's not possible anymore to send a mail.

Code:

Aug  1 11:19:30 server saslauthd[1482]: PAM [dlerror: /lib/libselinux.so.1: symbol regexec, version GLIBC_2.3.4 not defined in file libc.so.6 with link time reference]
Aug  1 11:19:30 server saslauthd[1482]: PAM adding faulty module: /lib/security/pam_unix.so
Aug  1 11:19:30 server saslauthd[1482]: DEBUG: auth_pam: pam_authenticate failed: Module is unknown
Aug  1 11:19:30 server saslauthd[1482]: do_auth         : auth failure: [user=webmaster] [service=smtp] [realm=] [mech=pam] [reason=PAM auth error]