winbind crashes on proxy server with samba + squid + ActiveDirectory

[Jean]

Binary package hint: winbind

soporte@ubuntu:~$ lsb_release -rd
Description: Ubuntu 8.04.2
Release: 8.04

soporte@ubuntu:~$ sudo apt-cache policy winbind
winbind:
  Instalados: 3.0.28a-1ubuntu4.7
  Candidato: 3.0.28a-1ubuntu4.7
  Tabla de versión:
 *** 3.0.28a-1ubuntu4.7 0
        500 http://ve.archive.ubuntu.com hardy-updates/main Packages
        100 /var/lib/dpkg/status
     3.0.28a-1ubuntu4.4 0
        500 http://security.ubuntu.com hardy-security/main Packages
     3.0.28a-1ubuntu4 0
        500 http://ve.archive.ubuntu.com hardy/main Packages

soporte@ubuntu:~$ sudo apt-cache policy samba
samba:
  Instalados: 3.0.28a-1ubuntu4.7
  Candidato: 3.0.28a-1ubuntu4.7
  Tabla de versión:
 *** 3.0.28a-1ubuntu4.7 0
        500 http://ve.archive.ubuntu.com hardy-updates/main Packages
        100 /var/lib/dpkg/status
     3.0.28a-1ubuntu4.4 0
        500 http://security.ubuntu.com hardy-security/main Packages
     3.0.28a-1ubuntu4 0
        500 http://ve.archive.ubuntu.com hardy/main Packages

soporte@ubuntu:~$ sudo apt-cache policy squid
squid:
  Instalados: 2.6.18-1ubuntu3
  Candidato: 2.6.18-1ubuntu3
  Tabla de versión:
 *** 2.6.18-1ubuntu3 0
        500 http://ve.archive.ubuntu.com hardy/main Packages
        100 /var/lib/dpkg/status

When winbind crashes, users are asked for username and password when they want to browse internet, and no matter what they write (correct or incorrect password and username) it just keep asking until they get a Cache Access Denied error.
Below the log sent by the server:

[Thread debugging using libthread_db enabled] [New Thread 0xb7aeb6d0 (LWP 20207)] 0xb7f03410 in __kernel_vsyscall () #0 0xb7f03410 in __kernel_vsyscall ()
#1 0xb7caa4d3 in waitpid () from /lib/tls/i686/cmov/libc.so.6
#2 0xb7c4d643 in ?? () from /lib/tls/i686/cmov/libc.so.6
#3 0x08123178 in smb_panic (why=0x8276ea4 "internal error") at lib/util.c:1639
#4 0x0810d99a in sig_fault (sig=6) at lib/fault.c:47
#5 <signal handler called>
#6 0xb7f03410 in __kernel_vsyscall ()
#7 0xb7c40085 in raise () from /lib/tls/i686/cmov/libc.so.6
#8 0xb7c41a01 in abort () from /lib/tls/i686/cmov/libc.so.6
#9 0xb7c3910e in __assert_fail () from /lib/tls/i686/cmov/libc.so.6 #10 0xb7d80bea in ldap_parse_result () from /usr/lib/libldap_r-2.4.so.2
#11 0x08239e4c in ads_do_paged_search_args (ads=0x82e46f0,
    bind_path=<value optimized out>, scope=0,
    expr=0x8265735 "(objectclass=*)", attrs=0xbf9428b0, args=0x0,
    res=0xbf9428b8, count=0xbf9427d4, cookie=0xbf9427d8) at libads/ldap.c:700
#12 0x0823a1cf in ads_do_search_all_args (ads=0x82e46f0,
    bind_path=0x8331290 "", scope=0, expr=0x8265735 "(objectclass=*)",
    attrs=0xbf9428b0, args=0x0, res=0xbf9428b8) at libads/ldap.c:772
#13 0x08243769 in ads_do_search_retry_internal (ads=0x82e46f0,
    bind_path=0x82aa7b5 "", scope=0, expr=0x8265735 "(objectclass=*)",
    attrs=0xbf9428b0, args=0x0, res=0xbf9428b8) at libads/ldap_utils.c:60
#14 0x08243cda in ads_do_search_retry (ads=0x82e46f0, bind_path=0x82aa7b5 "",
    scope=0, expr=0x8265735 "(objectclass=*)", attrs=0xbf9428b0,
    res=0xbf9428b8) at libads/ldap_utils.c:124
#15 0x08236ccc in ads_USN (ads=0x82e46f0, usn=0x832f014) at libads/ldap.c:2328
#16 0x080b4289 in sequence_number (domain=0x832eb90, seq=0x832f014)
    at nsswitch/winbindd_ads.c:1021
#17 0x08098a51 in refresh_sequence_number (domain=0x832eb90,
    force=<value optimized out>) at nsswitch/winbindd_cache.c:479
#18 0x08099079 in wcache_fetch (cache=0x832da08, domain=0x832eb90,
    format=0x826065d "NS/%s/%s") at nsswitch/winbindd_cache.c:601
#19 0x0809b6dd in name_to_sid (domain=0x832eb90, mem_ctx=0x82e4570,
    domain_name=0x832eb90 "EUROCIENCIA", name=0xbf942d28 "0", sid=0xbf942cc8,
    type=0xbf942d20) at nsswitch/winbindd_cache.c:1358 #20 0x08094311 in winbindd_lookup_sid_by_name (mem_ctx=0x82e4570,
    domain=0x832eb90, domain_name=0x832eb90 "EUROCIENCIA",
    name=0xbf942d28 "0", sid=0xbf942cc8, type=0xbf942d20)
    at nsswitch/winbindd_util.c:707
#21 0x08093e23 in winbindd_getgrnam (state=0x836f148)
    at nsswitch/winbindd_group.c:516
#22 0x0808b4f0 in request_recv (private_data=0x836f148, success=1)
    at nsswitch/winbindd.c:315
#23 0x0808b979 in rw_callback (event=0x836f154, flags=1)
    at nsswitch/winbindd.c:398
#24 0x0808c3f9 in main (argc=) at nsswitch/winbindd.c:835 The program is running. Quit anyway (and detach it)? (y or n) [answered Y; input not from terminal]