Aprox. once every week this kernel panic is thrown by smbd process. Could you please give me a hint what's going wrong here?

Jan 31 15:57:28 jupiter-ptp [1814449.289079] BUG: unable to handle kernel NULL pointer dereference at virtual address 00000008
Jan 31 15:57:28 jupiter-ptp [1814449.289085]  printing eip:
Jan 31 15:57:28 jupiter-ptp [1814449.289087] c10d61bc
Jan 31 15:57:28 jupiter-ptp [1814449.289089] *pde = 00000000
Jan 31 15:57:28 jupiter-ptp [1814449.289093] Oops: 0000 [#1]
Jan 31 15:57:28 jupiter-ptp [1814449.300548] SMP
Jan 31 15:57:28 jupiter-ptp [1814449.311593] Modules linked in: netconsole fat nfsd exportfs lockd nfs_acl sunrpc usb_storage smbfs raid456 md_mod xor eeprom i2c_piix4 i2c_core parport_pc parport floppy r8169 cfi_probe gen_probe scb2_flash mtdcore chipreg map_funcs tg3
Jan 31 15:57:28 jupiter-ptp [1814449.356523] CPU:    2
Jan 31 15:57:28 jupiter-ptp [1814449.356525] EIP:    0060:[<c10d61bc>]    Not tainted VLI
Jan 31 15:57:28 jupiter-ptp [1814449.356526] EFLAGS: 00010282   (2.6.18-gentoo-r2 #1)
Jan 31 15:57:28 jupiter-ptp [1814449.388304] EIP is at __rb_rotate_left+0xc/0x50
Jan 31 15:57:28 jupiter-ptp [1814449.398674] eax: f6e667c8   ebx: f6e667c8   ecx: 00000000   edx: 00000000
Jan 31 15:57:28 jupiter-ptp [1814449.408991] esi: f6e660c8   edi: c13c0ce0   ebp: c13c0ce0   esp: d5dbbecc
Jan 31 15:57:28 jupiter-ptp [1814449.419114] ds: 007b   es: 007b   ss: 0068
Jan 31 15:57:28 jupiter-ptp [1814449.428998] Process smbd (pid: 24872, ti=d5dba000 task=ed0d7000 task.ti=d5dba000)
Jan 31 15:57:28 jupiter-ptp [1814449.439002] Stack: da084148 f6e667c8 da0840c8 c10d62e1 da0840d0 00000000 da084194 f76c1600
Jan 31 15:57:28 jupiter-ptp [1814449.458702]        c10c12bd 0000001a da084140 000003f4 c12ddbc0 d5dbbf48 da0840c0 f6efa200
Jan 31 15:57:28 jupiter-ptp [1814449.478293]        ed0d7000 c10c1c9c ffffffff ed0d7000 1f3f0000 00000000 d5dbbf48 da0840c0
Jan 31 15:57:28 jupiter-ptp [1814449.498143] Call Trace:
Jan 31 15:57:28 jupiter-ptp [1814449.516986]  [<c10d62e1>] rb_insert_color+0x91/0xa7
Jan 31 15:57:28 jupiter-ptp [1814449.526302]  [<c10c12bd>] key_alloc+0x262/0x308
Jan 31 15:57:28 jupiter-ptp [1814449.535357]  [<c10c1c9c>] keyring_alloc+0x1e/0x4f
Jan 31 15:57:28 jupiter-ptp [1814449.544164]  [<c10c32c7>] alloc_uid_keyring+0x5b/0x82
Jan 31 15:57:28 jupiter-ptp [1814449.552889]  [<c124e2a7>] schedule+0x5ab/0x64c
Jan 31 15:57:28 jupiter-ptp [1814449.561367]  [<c102750b>] alloc_uid+0xc3/0x146
Jan 31 15:57:28 jupiter-ptp [1814449.569704]  [<c102aa16>] set_user+0xb/0x90
Jan 31 15:57:28 jupiter-ptp [1814449.577679]  [<c102ae78>] sys_setresuid+0x119/0x1d8
Jan 31 15:57:28 jupiter-ptp [1814449.585704]  [<c1002c49>] sysenter_past_esp+0x56/0x79
Jan 31 15:57:28 jupiter-ptp [1814449.593853] Code: e8 7c 63 f8 ff 8b 03 c7 04 83 00 00 00 00 48 85 c0 89 03 eb df b8 01 00 00 00 5b c3 90 90 90 57 89 d7 56 53 89 c3 8b 50 04 8b 30 <8b> 4a 08 83 e6 fc 85 c9 89 48 04 74 09 8b 01 83 e0 03 09 d8 89
Jan 31 15:57:28 jupiter-ptp [1814449.618960] EIP: [<c10d61bc>] __rb_rotate_left+0xc/0x50 SS:ESP 0068:d5dbbecc