Hello all. I have been running running centos 4.5 final for some time with any problems. Been running great, until today. System was frozen and /var/log/messages showed: Aug 15 23:01:28 mydomain kernel: Unable to handle kernel NULL pointer dereference at virtual address 00000000 Aug 15 23:01:28 mydomain kernel: printing eip: Aug 15 23:01:28 mydomain kernel: c01b2de4 Aug 15 23:01:28 mydomain kernel: *pde = 0790d067 Aug 15 23:01:28 mydomain kernel: Oops: 0000 [#1] Aug 15 23:01:28 mydomain kernel: Modules linked in: md5 ipv6 autofs4 i2c_dev i2c_core uhci_hcd 3c59x mii floppy ata_piix libata dm_snapshot dm_zero dm_mirr or ext3 jbd dm_mod 3w_xxxx sd_mod scsi_mod Aug 15 23:01:28 mydomain kernel: CPU: 0 Aug 15 23:01:28 mydomain kernel: EIP: 0060:[<c01b2de4>] Not tainted VLI Aug 15 23:01:28 mydomain kernel: EFLAGS: 00010246 (2.6.9-55.0.2.EL) Aug 15 23:01:28 mydomain kernel: EIP is at sysfs_readdir+0x1b2/0x216 Aug 15 23:01:28 mydomain kernel: eax: 00000000 ebx: c54ee0e0 ecx: ffffffff edx: 00000000 Aug 15 23:01:28 mydomain kernel: esi: c54ee0e4 edi: 00000000 ebp: c1be11e4 esp: c48f8f60 Aug 15 23:01:28 mydomain kernel: ds: 007b es: 007b ss: 0068 Aug 15 23:01:28 mydomain kernel: Process ossec-syscheckd (pid: 11762, threadinfo=c48f8000 task=c75a27e0) Aug 15 23:01:28 mydomain kernel: Stack: bff7125c c7ff5420 c0180d15 c48f8fa0 c717f920 c0372960 c717f920 c7f2b8b0 Aug 15 23:01:28 mydomain kernel: c0180d15 c018097e c48f8fa0 ffffffda 0856a5dc c717f920 00000000 c0180fcb Aug 15 23:01:28 mydomain kernel: 0856a644 0856a62c 00000f98 ffffffea 00000009 0856a5c0 002e8ff4 c48f8000 Aug 15 23:01:28 mydomain kernel: Call Trace: Aug 15 23:01:28 mydomain kernel: [<c0180d15>] filldir64+0x0/0x11a Aug 15 23:01:28 mydomain kernel: [<c0180d15>] filldir64+0x0/0x11a Aug 15 23:01:28 mydomain kernel: [<c018097e>] vfs_readdir+0x8a/0xb7 Aug 15 23:01:28 mydomain kernel: [<c0180fcb>] sys_getdents64+0x80/0xba Aug 15 23:01:28 mydomain kernel: [<c031af83>] syscall_call+0x7/0xb Aug 15 23:01:28 mydomain kernel: [<c031007b>] xfrm_parse_spi+0xb2/0xd3 Aug 15 23:01:28 mydomain kernel: Code: 04 89 69 0c 8b 75 00 8b 44 24 04 83 c0 0c 39 c6 74 73 8d 5e fc 83 7b 14 00 74 66 89 d8 e8 ec e2 ff ff 89 c2 83 c9 ff 31 c0 89 d7 <f2> ae f7 d1 49 0f b7 43 1c c1 e8 0c 50 ff 73 20 8b 44 24 18 ff Aug 15 23:01:28 mydomain kernel: <0>Fatal exception: panic in 5 seconds # uname -a Linux mydomain.com 2.6.9-55.0.2.EL #1 Tue Jun 26 14:08:18 EDT 2007 i686 i686 i386 GNU/Linux I don't understand the meaning of all of this? I'm trying to find the cause of why my system froze or crashed. The only recent change ( a few weeks ago ) that I did was an upgrade of ossec from 1.2 to 1.3. Does this log show or hint to the cause of the problem? Thank You Noel