[Dovecot] auth issues on centos5 with ldap backend

[Jurvis LaSalle]

Hi,

	We've had some issues with auth.  /var/log/secure is full of 1000s of  
these lines:

Jun  4 19:12:08 khan dovecot-auth: pam_unix(dovecot:auth):  
authentication failure; logname= uid=0 euid=0 tty=dovecot ruser=  
rhost=127.0.0.1  user=user123

Users can usually login OK with their ldap credentials, but  
occasionally logins slow to a crawl if not outright fail, esp people  
checking mail through Squirrelmail.  Things get better after a dovecot  
restart.  Googling around, I thought if we switched the order or  
disabled the second passdb we had configured for our dovecotadmin  
account, these failures would go away but that did not happen.  Any  
thoughts or additional info I can provide?  Pardon the unusual install  
prefix. We're trying to keep the source install separated from the  
ancient dovecot rpm shipped in rhel5.

Thanks,
Jurvis

[root at khan ~]# /etc/dovecot/sbin/dovecot -n
# 1.0.13: /etc/dovecot-1.0.13/etc/dovecot.conf
log_path: /var/log/dovecot.log
info_log_path: /var/log/dovecot-info.log
ssl_cert_file: /etc/pki/dovecot/certs/star.idi.harvard.edu.crt
ssl_key_file: /etc/pki/dovecot/private/star.idi.harvard.edu.key
login_dir: /etc/dovecot-1.0.13/var/run/dovecot/login
login_executable: /etc/dovecot/libexec/dovecot/imap-login
mail_location: maildir:/RAID5/mailboxes/%u
maildir_stat_dirs: yes
maildir_copy_with_hardlinks: yes
imap_client_workarounds: outlook-idle delay-newmail
auth default:
   executable: /etc/dovecot/libexec/dovecot/dovecot-auth
   master_user_separator: *
   debug: yes
   debug_passwords: yes
   passdb:
     driver: pam
     args: blocking=yes
   userdb:
     driver: passwd
     args: blocking=yes