Server crushed

[parser]

iptables was blocked for all ports, (only ping was work)
what is it?

Mar 13 19:26:05 first kernel: Unable to handle kernel NULL pointer dereference at virtual address 0000000c
Mar 13 19:26:05 first kernel: printing eip:
Mar 13 19:26:05 first kernel: c01b49c0
Mar 13 19:26:05 first kernel: *pde = 07dfb001
Mar 13 19:26:05 first kernel: Oops: 0000 [#1]
Mar 13 19:26:05 first kernel: SMP
Mar 13 19:26:05 first kernel: Modules linked in: ipt_owner md5 ipv6 parport_pc lp parport ipt_TOS iptable_mangle ip_conntrack_ftp ip_conntrack_irc ipt_REJECT ipt_LOG ipt_limit iptable_filter ipt_multiport ipt_state ip_conntrack ip_tables tg3 floppy sg dm_mod ohci_hcd video button battery ac ext3 jbd mptscsih mptbase sd_mod scsi_mod
Mar 13 19:26:05 first kernel: CPU: 0
Mar 13 19:26:05 first kernel: EIP: 0060:[<c01b49c0>] Not tainted VLI
Mar 13 19:26:05 first kernel: EFLAGS: 00010286 (2.6.10-1.770_FC2smp)
Mar 13 19:26:05 first kernel: EIP is at __rb_rotate_left+0x8/0x36
Mar 13 19:26:05 first kernel: eax: f57e6fc0 ebx: c04265e4 ecx: f57e6fc0 edx: 00000000
Mar 13 19:26:05 first kernel: esi: f57e6fc0 edi: e06940c0 ebp: c04265e4 esp: d032eed4
Mar 13 19:26:05 first kernel: ds: 007b es: 007b ss: 0068
Mar 13 19:26:05 first kernel: Process exim (pid: 30477, threadinfo=d032e000 task=e31eca60)
Mar 13 19:26:05 first kernel: Stack: c7c997c0 c01b4ad1 c7c997c0 c7c997c0 e06940cc 00007d12 c0197724 e06940c0
Mar 13 19:26:05 first kernel: 0000000f d032ef58 d032ef67 ffffffea c01977d8 00000017 00000000 00007d12
Mar 13 19:26:05 first kernel: c031f1e0 d032ef58 00000000 f5423280 00007d12 c0198951 ffffffff 001f0000
Mar 13 19:26:05 first kernel: Call Trace:
Mar 13 19:26:05 first kernel: [<c01b4ad1>] rb_insert_color+0xad/0xcc
Mar 13 19:26:05 first kernel: [<c0197724>] key_user_lookup+0xd4/0x101
Mar 13 19:26:05 first kernel: [<c01977d8>] key_alloc+0x53/0x2bf
Mar 13 19:26:05 first kernel: [<c0198951>] keyring_alloc+0x1a/0x48
Mar 13 19:26:05 first kernel: [<c0199ecf>] alloc_uid_keyring+0x2b/0x7b
Mar 13 19:26:05 first kernel: [<c0126002>] alloc_uid+0xb6/0x143
Mar 13 19:26:05 first kernel: [<c01294e9>] set_user+0xb/0x8c
Mar 13 19:26:05 first kernel: [<c0129631>] sys_setreuid+0xc7/0x174

[DigitalN]

Could be a hardware issue causing the 'Oops'

Did you recently upgrade the kernel or something, what led to the error - Just out of the blue? Is it a new machine?

I'd test the ram out RE: the 'Oops' to validate or otherwise it - download memtest and check it or have the datacenter do it for you.
Bit hard to trouble shoot on the info provided.