Description of problem:
kernel panic and total system lock-up

Version-Release number of selected component (if applicable):
2.6.9-67.0.20.ELsmp

How reproducible:
Occurred 3 times in 2 weeks. Reported at CentOS: 
http://www.centos.org/modules/newbb/viewtopic.php?post_id=53184&topic_id=15191&forum=27#forumpost53184
by 3 independent users (2 CentOS and 1 RHEL)
When downgrading to the previous -15 kernel, no crashes in 4 days (=so far).

Steps to Reproduce:
1.Install kernel -20 or upgrade from prevous -15 kernel.
2.According CentOS forum above related to clamd or Surgemail (mail software), or
hardware depentdent
3.
  
Actual results:
Jul  9 01:29:37 server kernel: ------------[ cut here ]------------
Jul  9 01:29:37 server kernel: kernel BUG at kernel/exit.c:881!
Jul  9 01:29:37 server kernel: invalid operand: 0000 [#1]
Jul  9 01:29:37 server kernel: SMP 
Jul  9 01:29:37 server kernel: Modules linked in: nfsd exportfs lockd nfs_acl
parport_pc lp parport autofs4 i2c_dev i2c_core sunrpc dm_mirror dm_mod button
battery ac md5 ipv6 joydev ohci_hcd ehci_hcd forcedeth k8_edac edac_mc
snd_ymfpci snd_ac97_codec snd_pcm_oss snd_mixer_oss snd_pcm snd_opl3_lib
snd_timer snd_hwdep snd_page_alloc snd_mpu401_uart snd_rawmidi snd_seq_device
snd soundcore 3c59x mii floppy ext3 jbd raid1 sata_nv ahci libata sd_mod scsi_mod
Jul  9 01:29:37 server kernel: CPU:    1
Jul  9 01:29:37 server kernel: EIP:    0060:[<c01249e8>]    Not tainted VLI
Jul  9 01:29:37 server kernel: EFLAGS: 00010046   (2.6.9-67.0.20.ELsmp) 
Jul  9 01:29:37 server kernel: EIP is at next_thread+0xc/0x3f
Jul  9 01:29:37 server kernel: eax: 00000000   ebx: f775d6b0   ecx: 0057cff4  
edx: f77a4170
Jul  9 01:29:37 server kernel: esi: 00002ef9   edi: 00024e02   ebp: b7b81b00  
esp: ef481f8c
Jul  9 01:29:37 server kernel: ds: 007b   es: 007b   ss: 0068
Jul  9 01:29:37 server kernel: Process surgemail (pid: 3967, threadinfo=ef481000
task=f775d6b0)
Jul  9 01:29:37 server kernel: Stack: c012f19a 00000246 00000000 b7b81b28
b7b81b20 ef481fa8 b7b81b20 00000000 
Jul  9 01:29:37 server kernel:        c01262f8 b7b81b00 00000064 00000028
ef481000 c02d8b77 b7b81b00 0057cff4 
Jul  9 01:29:37 server kernel:        0057cff4 00000064 00000028 b7b81b18
0000002b 0000007b 0000007b 0000002b 
Jul  9 01:29:37 server kernel: Call Trace:
Jul  9 01:29:37 server kernel:  [<c012f19a>] sys_times+0x56/0x1c5
Jul  9 01:29:37 server kernel:  [<c01262f8>] sys_gettimeofday+0x9a/0xac
Jul  9 01:29:37 server kernel:  [<c02d8b77>] syscall_call+0x7/0xb
Jul  9 01:29:37 server kernel: Code: 85 c0 89 d3 74 05 e8 f3 9e ff ff 53 e8 df
fb ff ff 0f b6 44 24 04 c1 e0 08 50 e8 d1 fb ff ff 89 c2 8b 80 f0 04 00 00 85 c0
75 08 <0f> 0b 71 03 c0 a5 2e c0 0f b6 80 04 05 00 00 84 c0 7e 14 a1 00 
Jul  9 01:29:37 server kernel:  <0>Fatal exception: panic in 5 seconds

Expected results:
No panic, normal operation

Additional info: