[CentOS] Kernel Panic

Greetings,

Had a system lock up last night.  I've captured the following data
from the logs:

Jan 31 18:13:04 webserver kernel: Unable to handle kernel NULL pointer dereference at virtual address 00000400
Jan 31 18:13:04 webserver kernel:  printing eip:
Jan 31 18:13:04 webserver kernel: c013f952
Jan 31 18:13:04 webserver kernel: *pde = 20ae6001
Jan 31 18:13:04 webserver kernel: Oops: 0000 [#1]
Jan 31 18:13:04 webserver kernel: SMP
Jan 31 18:13:04 webserver kernel: Modules linked in: loop md5 ipv6 autofs4 sunrpc ip_conntrack_ftp ipt_REJECT ipt_state ip_conntrack iptable_filter ip_tables microcode dm_mod button battery ac uhci_hcd hw_random e100 mii ext3 jbd ata_piix sata_promise libata sd_mod scsi_mod
Jan 31 18:13:04 webserver kernel: CPU:    0
Jan 31 18:13:04 webserver kernel: EIP:    0060:[<c013f952>]    Not tainted VLI
Jan 31 18:13:04 webserver kernel: EFLAGS: 00010006   (2.6.9-22.0.1.ELsmp)
Jan 31 18:13:04 webserver kernel: EIP is at find_lock_page+0x22/0x9d
Jan 31 18:13:04 webserver kernel: eax: 00000400   ebx: 00000400   ecx: b7ff5000   edx: 00000400
Jan 31 18:13:04 webserver kernel: esi: e1f88a48   edi: e1c7bde0   ebp: 0000145b   esp: e1c7bd90
Jan 31 18:13:04 webserver kernel: ds: 007b   es: 007b   ss: 0068
Jan 31 18:13:04 webserver kernel: Process popper (pid: 23878, threadinfo=e1c7b000 task=f7428eb0)
Jan 31 18:13:04 webserver kernel: Stack: 00000000 e1c7bdd8 e1c7bde0 0000145b c014107c f7f42e00 0000005b 00000000
Jan 31 18:13:04 webserver kernel:        b7ff405b 00000fa5 e1f88998 f88d3820 e1f88a48 edb09280 00000001 e1c7bef8
Jan 31 18:13:04 webserver kernel:        00000000 e1c7bebc 00000000 2f000000 00000000 00000000 e1c7be0c 00000000
Jan 31 18:13:04 webserver kernel: Call Trace:
Jan 31 18:13:04 webserver kernel:  [<c014107c>] generic_file_buffered_write+0xe5/0x47c
Jan 31 18:13:04 webserver kernel:  [<c012625c>] current_fs_time+0x44/0x4c
Jan 31 18:13:04 webserver kernel:  [<c012625c>] current_fs_time+0x44/0x4c
Jan 31 18:13:04 webserver kernel:  [<c014179c>] __generic_file_aio_write_nolock+0x389/0x3b7
Jan 31 18:13:04 webserver kernel:  [<c0141803>] generic_file_aio_write_nolock+0x39/0x7f
Jan 31 18:13:04 webserver kernel:  [<c01419ed>] generic_file_aio_write+0x72/0xc6
Jan 31 18:13:04 webserver kernel:  [<f88b9d7a>] ext3_file_write+0x19/0x8b [ext3]
Jan 31 18:13:04 webserver kernel:  [<c0159c3c>] do_sync_write+0x97/0xc9
Jan 31 18:13:04 webserver kernel:  [<c011fec9>] autoremove_wake_function+0x0/0x2d
Jan 31 18:13:04 webserver kernel:  [<c02cf5cb>] __cond_resched+0x14/0x39
Jan 31 18:13:04 webserver kernel:  [<c015962c>] generic_file_llseek+0x30/0xcb
Jan 31 18:13:04 webserver kernel:  [<c0159d24>] vfs_write+0xb6/0xe2
Jan 31 18:13:04 webserver kernel:  [<c0159dee>] sys_write+0x3c/0x62
Jan 31 18:13:04 webserver kernel:  [<c02d0fb7>] syscall_call+0x7/0xb
Jan 31 18:13:04 webserver kernel:  [<c02d007b>] __lock_text_end+0x232/0x100fJan 31 18:13:04 webserver kernel: Code: 04 19 00 89 d8 5b 5e 5f c3 55 89 d5 57 56 89 c6 8d 40 10 53 e8 d6 02 19 00 8d 46 04 89 ea e8 11 fe 07 00 85 c0 89 c3 74 6e 89 c2 <8b> 00 f6 c4 80 74 03 8b 53 0c f0 ff 42 04 f0 0f ba 2b 00 19 c0
Jan 31 18:13:04 webserver kernel:  <0>Fatal exception: panic in 5 seconds
Jan 31 18:13:05 webserver crond(pam_unix)[23911]: session closed for user root
  
What's the best way to track down the source of this panic?

-- 
Best regards,
 Mike