[Dovecot] Error while login to dovecot server:

[Hari]

Hi Friends,
I'm running postfix 2.2.10, dovecot-0.99.11 and openldap -2.2.13 in my 
organization. Here, all my postfix, dovecot, saslauthd, depends on ldap 
only. Means ldap is acting as a centralized database for user information.
In this picture everything is working fine except user login to dovecot for 
downloading their mails. Actually they can't able to login to the server 
from client like outlook express. Instead thay are geting error like "server 
closed the connection...".
Here i'm attaching my dovecot conf file and error log.
Kindly give any suggesions where i'm making mistake.
==========================================
Version Details:
Dovecot:     dovecot-0.99.11
Postfix:        postfix-2.2.10
Openldap:   openldap-2.2.13
==========================================
Dovecot Configuration file:

"dovecot-ldap.conf "
hosts = localhost
dn = cn=Manager,dc=panafnet,dc=com
dnpass = hcl123
ldap_version = 3
base = dc=panafnet,dc=com
deref = never
scope = subtree
user_attrs = uid,userPassword
user_filter = (&(uid=%u))
pass_attrs = uid,userPassword
pass_filter = (&(uid=%u))
default_pass_scheme = PLAIN
user_global_uid = 101
user_global_gid = 12
================
"dovecot.conf"
protocols = imap pop3
imap_listen = [::]
pop3_listen = [::]
disable_plaintext_auth = no
login_dir = /var/run/dovecot-login
login = imap
login_user = dovecot
first_valid_uid = 101
last_valid_uid = 101
first_valid_gid = 12
last_valid_gid = 12
mbox_locks = fcntl
auth = default
auth_mechanisms = plain
auth_userdb = ldap /etc/dovecot-ldap.conf
auth_passdb = ldap /etc/dovecot-ldap.conf
auth_executable = /usr/libexec/dovecot/dovecot-auth
auth_user = dovecot-auth
=================================================================
Error log while user trying to login from client like outlook express:
==========
Jul  8 17:53:30 experts dovecot: chdir(vasuda) failed with uid 101: 
Permission denied
Jul  8 17:53:30 experts imap-login: Login: vasuda [::ffff:192.168.117.25]
Jul  8 17:53:30 experts dovecot: child 7921 (imap) returned error 89
================================================================
slapd.log
==========
Jul  8 17:53:30 experts slapd[7249]: conn=21 op=1 SRCH 
base="dc=panafnet,dc=com" scope=2 deref=0 filter="(&(uid=vasuda))"
Jul  8 17:53:30 experts slapd[7249]: conn=21 op=1 SRCH attr=uid userPassword
Jul  8 17:53:30 experts slapd[7249]: conn=21 op=1 SEARCH RESULT tag=101 
err=0 nentries=1 text=
Jul  8 17:53:30 experts slapd[7249]: conn=21 op=2 SRCH 
base="dc=panafnet,dc=com" scope=2 deref=0 filter="(&(uid=vasuda))"
Jul  8 17:53:30 experts slapd[7249]: conn=21 op=2 SRCH attr=uid userPassword
Jul  8 17:53:30 experts slapd[7249]: conn=21 op=2 SEARCH RESULT tag=101 
err=0 nentries=1 text=
Jul  8 17:53:30 experts slapd[7249]: conn=21 op=2 SRCH 
base="dc=panafnet,dc=com" scope=2 deref=0 filter="(&(uid=vasuda))"
Jul  8 17:53:30 experts slapd[7249]: conn=21 op=2 SRCH attr=uid userPassword
Jul  8 17:53:30 experts slapd[7249]: conn=21 op=2 SEARCH RESULT tag=101 
err=0 nentries=1 text=
================================================================
Note: The /var/spool/mail (the mailbox location) where all the user mailbox 
located is owned by dovecot-auth : mail. The uid is 101 and gid is 12.
=============================================================================================================
----------------
With Thanks & Regards,
Hari Narayanan S
Solution Centre,
H.O.Marketting,
HCL Infosystems Ltd.,
Secotr-11, Noida-201301.