could you test 3.0.20?  Or at least recompile 3.0.14a
with "configure --enable-debug" ?  Twithout a good backtrace 
or reproroducible test case, it's going to be hard to do 
anything with this.

My current version installed from binary packages. Now I am trying to use
builded from sources version. Debuging options enabled. All news will come ASAP.

It crashed once again. This is what I have:

[2005/09/06 10:07:48, 0] lib/fault.c:fault_report(36)
  ===============================================================
[2005/09/06 10:07:48, 0] lib/fault.c:fault_report(37)
  INTERNAL ERROR: Signal 11 in pid 21905 (3.0.14a)
  Please read the appendix Bugs of the Samba HOWTO collection
[2005/09/06 10:07:48, 0] lib/fault.c:fault_report(39)
  ===============================================================
[2005/09/06 10:07:48, 0] lib/util.c:smb_panic2(1485)
  smb_panic(): calling panic action [/usr/share/samba/panic-action 21905]
[2005/09/06 10:07:52, 0] lib/util.c:smb_panic2(1493)
  smb_panic(): action returned status 0
[2005/09/06 10:07:52, 0] lib/util.c:smb_panic2(1495)
  PANIC: internal error
[2005/09/06 10:07:52, 0] lib/util.c:smb_panic2(1503)
  BACKTRACE: 36 stack frames:
   #0 /usr/local/samba/sbin/smbd(smb_panic2+0x1f5) [0x82188e0]
   #1 /usr/local/samba/sbin/smbd(smb_panic+0x19) [0x82186e9]
   #2 /usr/local/samba/sbin/smbd [0x8202ab1]
   #3 /usr/local/samba/sbin/smbd [0x8202b29]
   #4 /lib/libpthread.so.0 [0x40272825]
   #5 /lib/libc.so.6 [0x400e06f8]
   #6 /usr/lib/libldap_r.so.2(ldap_int_open_connection+0x253) [0x40028593]
   #7 /usr/lib/libldap_r.so.2(ldap_new_connection+0x89) [0x4003a299]
   #8 /usr/lib/libldap_r.so.2(ldap_open_defconn+0x41) [0x40027f11]
   #9 /usr/lib/libldap_r.so.2(ldap_send_initial_request+0x8f) [0x40039e0f]
   #10 /usr/lib/libldap_r.so.2(ldap_sasl_bind+0x177) [0x40030137]
   #11 /usr/lib/libldap_r.so.2(ldap_sasl_bind_s+0x9b) [0x4003040b]
   #12 /usr/lib/libldap_r.so.2(ldap_simple_bind_s+0x6c) [0x40030c7c]
   #13 /usr/local/samba/sbin/smbd [0x828fa20]
   #14 /usr/local/samba/sbin/smbd [0x828fed9]
   #15 /usr/local/samba/sbin/smbd [0x829014c]
   #16 /usr/local/samba/sbin/smbd(smbldap_search+0x2d9) [0x82904ff]
   #17 /usr/local/samba/sbin/smbd(smbldap_search_suffix+0x47) [0x8290ada]
   #18 /usr/local/samba/sbin/smbd(ldapsam_search_suffix_by_name+0xd4) [0x81e6765]
   #19 /usr/local/samba/sbin/smbd [0x81ea276]
   #20 /usr/local/samba/sbin/smbd [0x81dfbca]
   #21 /usr/local/samba/sbin/smbd(pdb_getsampwnam+0x47) [0x81e1e63]
   #22 /usr/local/samba/sbin/smbd(local_uid_to_sid+0x136) [0x81db7e4]
   #23 /usr/local/samba/sbin/smbd(uid_to_sid+0x1c9) [0x81e5009]
   #24 /usr/local/samba/sbin/smbd [0x80dc4e2]
   #25 /usr/local/samba/sbin/smbd(get_nt_acl+0x3d5) [0x80e146e]
   #26 /usr/local/samba/sbin/smbd(vfswrap_fget_nt_acl+0x1f) [0x80d9d87]
   #27 /usr/local/samba/sbin/smbd [0x80a3ce7]
   #28 /usr/local/samba/sbin/smbd(reply_nttrans+0xd88) [0x80a5f88]
   #29 /usr/local/samba/sbin/smbd [0x80e786b]
   #30 /usr/local/samba/sbin/smbd [0x80e7941]
   #31 /usr/local/samba/sbin/smbd(process_smb+0x215) [0x80e7cd8]
   #32 /usr/local/samba/sbin/smbd(smbd_process+0x195) [0x80e8af2]
   #33 /usr/local/samba/sbin/smbd(main+0x8a2) [0x8294084]
   #34 /lib/libc.so.6(__libc_start_main+0xc6) [0x400cce36]
   #35 /usr/local/samba/sbin/smbd [0x8077751]

this is a backtrace:

Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 16384 (LWP 21905)]
0x4015e808 in waitpid () from /lib/libc.so.6
#0  0x4015e808 in waitpid () from /lib/libc.so.6
#1  0x401e6880 in ?? () from /lib/libc.so.6
#2  0x400f74c2 in strtold_l () from /lib/libc.so.6
#3  0x08218783 in smb_panic2 (why=0x82f2a1e "internal error", 
    decrement_pid_count=1) at lib/util.c:1486
#4  0x082186e9 in smb_panic (why=0x82f2a1e "internal error") at lib/util.c:1445
#5  0x08202ab1 in fault_report (sig=11) at lib/fault.c:41
#6  0x08202b29 in sig_fault (sig=11) at lib/fault.c:64
#7  0x40272825 in __pthread_sighandler () from /lib/libpthread.so.0
#8  <signal handler called>
#9  0x4103c50f in ?? ()
#10 0x0844dcf0 in ?? ()
#11 0x000004f8 in ?? ()
#12 0x0844f0a8 in ?? ()
#13 0x00000010 in ?? ()
#14 0x00000000 in ?? ()
#15 0x00000000 in ?? ()
#16 0x4018129d in fcntl () from /lib/libc.so.6
#17 0x40028593 in ldap_int_open_connection () from /usr/lib/libldap_r.so.2
#18 0x4003a299 in ldap_new_connection () from /usr/lib/libldap_r.so.2
#19 0x40027f11 in ldap_open_defconn () from /usr/lib/libldap_r.so.2
#20 0x40039e0f in ldap_send_initial_request () from /usr/lib/libldap_r.so.2
#21 0x40030137 in ldap_sasl_bind () from /usr/lib/libldap_r.so.2
#22 0x4003040b in ldap_sasl_bind_s () from /usr/lib/libldap_r.so.2
#23 0x40030c7c in ldap_simple_bind_s () from /usr/lib/libldap_r.so.2
#24 0x0828fa20 in smbldap_connect_system (ldap_state=0x83a88e0, 
    ldap_struct=0x844dcf0) at lib/smbldap.c:842
#25 0x0828fed9 in smbldap_open (ldap_state=0x83a88e0) at lib/smbldap.c:920
#26 0x0829014c in another_ldap_try (ldap_state=0x83a88e0, rc=0xbffff0fc, 
    attempts=0xbffff0f8, endtime=1125986868) at lib/smbldap.c:997
#27 0x082904ff in smbldap_search (ldap_state=0x83a88e0, 
    base=0x844d958 "dc=nordcomp,dc=ru", scope=2, 
    filter=0xbffff170 "(&(uid=kirusheva)(objectclass=sambaSamAccount))", 
    attrs=0x844db50, attrsonly=0, res=0xbffff5ac) at lib/smbldap.c:1067
#28 0x08290ada in smbldap_search_suffix (ldap_state=0x83a88e0, 
    filter=0xbffff170 "(&(uid=kirusheva)(objectclass=sambaSamAccount))", 
    search_attr=0x844db50, result=0xbffff5ac) at lib/smbldap.c:1169
#29 0x081e6765 in ldapsam_search_suffix_by_name (ldap_state=0x83a8860, 
    user=0x844d550 "kirusheva", result=0xbffff5ac, attr=0x844db50)
    at passdb/pdb_ldap.c:213
#30 0x081ea276 in ldapsam_getsampwnam (my_methods=0x83a87c0, user=0x844d9f0, 
    sname=0x844d550 "kirusheva") at passdb/pdb_ldap.c:1325
#31 0x081dfbca in context_getsampwnam (context=0x83a85f0, sam_acct=0x844d9f0, 
    username=0x844d550 "kirusheva") at passdb/pdb_interface.c:198
#32 0x081e1e63 in pdb_getsampwnam (sam_acct=0x844d9f0, 
    username=0x844d550 "kirusheva") at passdb/pdb_interface.c:943
#33 0x081db7e4 in local_uid_to_sid (psid=0xbffff890, uid=1010)
    at passdb/passdb.c:1146
#34 0x081e5009 in uid_to_sid (psid=0xbffff890, uid=1010)
    at passdb/lookup_sid.c:325
#35 0x080dc4e2 in create_file_sids (psbuf=0xbffff8f0, powner_sid=0xbffff890, 
    pgroup_sid=0xbffff840) at smbd/posix_acls.c:659
#36 0x080e146e in get_nt_acl (fsp=0x844d4a0, security_info=4, 
    ppdesc=0xbffff9cc) at smbd/posix_acls.c:2707
#37 0x080d9d87 in vfswrap_fget_nt_acl (handle=0x0, fsp=0x844d4a0, fd=-1, 
    security_info=4, ppdesc=0xbffff9cc) at smbd/vfs-wrap.c:817
#38 0x080a3ce7 in call_nt_transact_query_security_desc (conn=0x840ecf8, 
    inbuf=0x406b4008 "", outbuf=0x406d5008 "", length=88, bufsize=131072, 
    ppsetup=0xbffffa78, setup_count=0, ppparams=0xbffffa80, parameter_count=8, 
    ppdata=0xbffffa7c, data_count=0, max_data_count=0) at smbd/nttrans.c:1969
#39 0x080a5f88 in reply_nttrans (conn=0x840ecf8, inbuf=0x406b4008 "", 
    outbuf=0x406d5008 "", length=88, bufsize=131072) at smbd/nttrans.c:2967
#40 0x080e786b in switch_message (type=160, inbuf=0x406b4008 "", 
    outbuf=0x406d5008 "", size=88, bufsize=131072) at smbd/process.c:968
#41 0x080e7941 in construct_reply (inbuf=0x406b4008 "", outbuf=0x406d5008 "", 
    size=88, bufsize=131072) at smbd/process.c:998
#42 0x080e7cd8 in process_smb (inbuf=0x406b4008 "", outbuf=0x406d5008 "")
    at smbd/process.c:1098
#43 0x080e8af2 in smbd_process () at smbd/process.c:1558
#44 0x08294084 in main (argc=4, argv=0xbffffd74) at smbd/server.c:951

Hmmm...the crash is in the openldap client libs.  We might be 
causing that however, but i don't have sufficient information 
in the backtrace to know for sure.  Have you tested 3.0.20?
If so, is the bug still present?

3.0.20 not tested. Bug appears only 4 times (for 2 weeks). All other time - no
problems. Now installing 3.0.20.

Now 3.0.20 crashed.

Backtrace:
Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 16384 (LWP 14018)]
0x4015f808 in waitpid () from /lib/libc.so.6
#0  0x4015f808 in waitpid () from /lib/libc.so.6
#1  0x401e7880 in ?? () from /lib/libc.so.6
#2  0x400f84c2 in strtold_l () from /lib/libc.so.6
#3  0x08239275 in smb_panic2 (why=0x8322d9e "internal error", 
    decrement_pid_count=1) at lib/util.c:1539
#4  0x082391db in smb_panic (why=0x8322d9e "internal error") at lib/util.c:1500
#5  0x08222c3d in fault_report (sig=11) at lib/fault.c:41
#6  0x08222cb5 in sig_fault (sig=11) at lib/fault.c:64
#7  0x40273825 in __pthread_sighandler () from /lib/libpthread.so.0
#8  <signal handler called>
#9  0x4017bf92 in freeaddrinfo () from /lib/libc.so.6
#10 0x4003d47d in ldap_connect_to_host () from /usr/lib/libldap_r.so.2
#11 0x40029593 in ldap_int_open_connection () from /usr/lib/libldap_r.so.2
#12 0x4003b299 in ldap_new_connection () from /usr/lib/libldap_r.so.2
#13 0x40028f11 in ldap_open_defconn () from /usr/lib/libldap_r.so.2
#14 0x4003ae0f in ldap_send_initial_request () from /usr/lib/libldap_r.so.2
#15 0x40031137 in ldap_sasl_bind () from /usr/lib/libldap_r.so.2
#16 0x4003140b in ldap_sasl_bind_s () from /usr/lib/libldap_r.so.2
#17 0x40031c7c in ldap_simple_bind_s () from /usr/lib/libldap_r.so.2
#18 0x082b99fc in smbldap_connect_system (ldap_state=0x83dad78, 
    ldap_struct=0x84ab538) at lib/smbldap.c:780
#19 0x082b9ebf in smbldap_open (ldap_state=0x83dad78) at lib/smbldap.c:860
#20 0x082ba132 in another_ldap_try (ldap_state=0x83dad78, rc=0xbfffe9ec, 
    attempts=0xbfffe9e8, endtime=1126867697) at lib/smbldap.c:937
#21 0x082ba51e in smbldap_search_ext (ldap_state=0x83dad78, 
    base=0x84ad270 "dc=nordcomp,dc=ru", scope=2, 
    filter=0xbfffeba0
"(&(sambaSID=S-1-5-21-1511076964-877292650-2087880317-513)(objectclass=sambaSamAccount))",
attrs=0x84ae950, attrsonly=0, sctrls=0x0, 
    cctrls=0x0, sizelimit=0, res=0xbffff128) at lib/smbldap.c:1026
#22 0x082ba628 in smbldap_search (ldap_state=0x83dad78, 
    base=0x84ad270 "dc=nordcomp,dc=ru", scope=2, 
    filter=0xbfffeba0
"(&(sambaSID=S-1-5-21-1511076964-877292650-2087880317-513)(objectclass=sambaSamAccount))",
attrs=0x84ae950, attrsonly=0, res=0xbffff128)
    at lib/smbldap.c:1050
#23 0x082bb064 in smbldap_search_suffix (ldap_state=0x83dad78, 
    filter=0xbfffeba0
"(&(sambaSID=S-1-5-21-1511076964-877292650-2087880317-513)(objectclass=sambaSamAccount))",
search_attr=0x84ae950, result=0xbffff128)
    at lib/smbldap.c:1239
#24 0x0820430d in ldapsam_search_suffix_by_sid (ldap_state=0x83dace0, 
    sid=0x84ae350, result=0xbffff128, attr=0x84ae950) at passdb/pdb_ldap.c:252
#25 0x08207ffb in ldapsam_get_ldap_user_by_sid (ldap_state=0x83dace0, 
    sid=0x84ae350, result=0xbffff128) at passdb/pdb_ldap.c:1372
#26 0x082080d3 in ldapsam_getsampwsid (my_methods=0x83dac20, user=0x84aabb0, 
    sid=0x84ae350) at passdb/pdb_ldap.c:1408
#27 0x081fc658 in context_getsampwsid (context=0x83daa68, sam_acct=0x84aabb0, 
    sid=0x84ae350) at passdb/pdb_interface.c:222
#28 0x081feb1c in pdb_getsampwsid (sam_acct=0x84aabb0, sid=0x84ae350)
    at passdb/pdb_interface.c:1015
#29 0x081f84c6 in local_sid_to_uid (puid=0x84ae39c, psid=0x84ae350, 
    name_type=0xbffff1ec) at passdb/passdb.c:1193
#30 0x08202f80 in sid_to_uid (psid=0x84ae350, puid=0x84ae39c)
    at passdb/lookup_sid.c:395
#31 0x080e71d6 in create_canon_ace_lists (fsp=0x84ab3e8, pst=0xbffff8b0, 
    pfile_owner_sid=0xbffff860, pfile_grp_sid=0xbffff810, 
    ppfile_ace=0xbffff7a0, ppdir_ace=0xbffff79c, dacl=0x84a7b08)
    at smbd/posix_acls.c:1393
#32 0x080e8095 in unpack_canon_ace (fsp=0x84ab3e8, pst=0xbffff8b0, 
    pfile_owner_sid=0xbffff860, pfile_grp_sid=0xbffff810, 
    ppfile_ace=0xbffff80c, ppdir_ace=0xbffff808, security_info_sent=7, 
    psd=0x84aa090) at smbd/posix_acls.c:1941
#33 0x080ebcad in set_nt_acl (fsp=0x84ab3e8, security_info_sent=7, 
    psd=0x84aa090) at smbd/posix_acls.c:3167
#34 0x080e2e87 in vfswrap_fset_nt_acl (handle=0x0, fsp=0x84ab3e8, fd=-1, 
    security_info_sent=7, psd=0x84aa090) at smbd/vfs-wrap.c:837
#35 0x080a4fa9 in set_sd (fsp=0x84ab3e8, data=0x84ad098 "\001", sd_len=176, 
    security_info_sent=7) at smbd/nttrans.c:1041
#36 0x080a885e in call_nt_transact_set_security_desc (conn=0x844a330, 
    inbuf=0x406b4008 "", outbuf=0x406d5008 "", length=264, bufsize=131072, 
    ppsetup=0xbffffa78, setup_count=0, ppparams=0xbffffa80, parameter_count=8, 
    ppdata=0xbffffa7c, data_count=176, max_data_count=0) at smbd/nttrans.c:2087
#37 0x080aa4e0 in reply_nttrans (conn=0x844a330, inbuf=0x406b4008 "", 
    outbuf=0x406d5008 "", length=264, bufsize=131072) at smbd/nttrans.c:2990
#38 0x080f10f4 in switch_message (type=160, inbuf=0x406b4008 "", 
    outbuf=0x406d5008 "", size=264, bufsize=131072) at smbd/process.c:991
#39 0x080f11ca in construct_reply (inbuf=0x406b4008 "", outbuf=0x406d5008 "", 
    size=264, bufsize=131072) at smbd/process.c:1021
#40 0x080f1561 in process_smb (inbuf=0x406b4008 "", outbuf=0x406d5008 "")
    at smbd/process.c:1121
#41 0x080f24b8 in smbd_process () at smbd/process.c:1670
#42 0x082be690 in main (argc=4, argv=0xbffffd74) at smbd/server.c:963

Again this comes from deep inside the LDAP libraries. There is no generic Samba
bug I'm aware of that causes this. You say it only happens very rarely, this
makes it a bit difficult to track down.

It might be helpful if you could run your smbd under valgrind for a test. This
will make the system very slow, but it might expose invalid memory access that
sometimes causes a crash. Doing one or two domain logins and other tests under
valgrind in non-production times would be great. You get valgrind from
www.valgrind.org.

Please run it with the following options:

valgrind --tool=memcheck --leak-check=yes -v --num-callers=20 \
--trace-children=yes --log-file=/tmp/smbd.vg smbd -D

and upload the resulting file.

Thanks a lot,

Volker

Created attachment 1454 [details]
Valgrind logfile

Im unable to login to domain while valgrind test.

Created attachment 1455 [details]
Another valgrind logfile, after few tests

Under valgrind it works really slow. Even unable to login, but localy I make
few tests - even directory browsing became a problem (very slow browsing)...

So, what about valgrind logs? 
About crash: not all my stations crash, bot only those, who have one tool. This
tool produce high network traffic with small packets. It is a Database, and his
files placed on samba server. Other stations without this database (or use it
rarely) works fine.

severity should be determined by the developers and not the reporter.

please reopen if this is reproducable with modern samba versions.