chmod or chown problem

Jul 17 17:51:14 localhost [85337.132127] Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP: 
Jul 17 17:51:14 localhost [85337.132134]  [<0000000000000000>]
Jul 17 17:51:14 localhost [85337.132140] PGD 21e4d067 PUD 2abf5067 PMD 0 
Jul 17 17:51:14 localhost [85337.132145] Oops: 0010 [1] PREEMPT SMP 
Jul 17 17:51:14 localhost [85337.132149] CPU 1 
Jul 17 17:51:14 localhost [85337.132152] Modules linked in: truecrypt snd_pcm_oss snd_mixer_oss snd_seq_oss snd_seq_device snd_seq_midi_event snd_seq ieee80211_crypt_wep ieee80211_crypt nvidia(P) i2c_i801 sdhci mmc_core iwl3945 mac80211 uhci_hcd ehci_hcd snd_hda_intel snd_pcm snd_timer snd snd_page_alloc
Jul 17 17:51:14 localhost [85337.132172] Pid: 17981:#0, comm: python Tainted: P       2.6.22-electric1 #1
Jul 17 17:51:14 localhost [85337.132174] RIP: 0010:[<0000000000000000>]  [<0000000000000000>]
Jul 17 17:51:14 localhost [85337.132178] RSP: 0018:ffff8100078db910  EFLAGS: 00010206
Jul 17 17:51:14 localhost [85337.132181] RAX: 0000000000000005 RBX: ffffffff8052d4f0 RCX: 0000000000000005
Jul 17 17:51:14 localhost [85337.132185] RDX: 0000000000000000 RSI: ffff810001471a30 RDI: ffff81004bf50b80
Jul 17 17:51:14 localhost [85337.132188] RBP: ffff810001471a30 R08: ffffffff80661a06 R09: 000000000000a57f
Jul 17 17:51:14 localhost [85337.132191] R10: 0000000000000000 R11: ffff81003989c560 R12: 0000000000000005
Jul 17 17:51:14 localhost [85337.132195] R13: 0000000000000000 R14: ffff810001000000 R15: 0000000000000000
Jul 17 17:51:14 localhost [85337.132198] FS:  00002b918e329120(0000) GS:ffff81005fe2fe40(0000) knlGS:0000000000000000
Jul 17 17:51:14 localhost [85337.132202] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
Jul 17 17:51:14 localhost [85337.132205] CR2: 0000000000000000 CR3: 000000001e301000 CR4: 00000000000006e0
Jul 17 17:51:14 localhost [85337.132209] Process python (pid: 17981[#0], threadinfo ffff8100078da000, task ffff810058d36800)
Jul 17 17:51:14 localhost [85337.132211] Stack:  ffffffff80265621 00000010000280d2 ffff81004bf50bb8 000000003fc0adb0
Jul 17 17:51:14 localhost [85337.132218]  ffff81004bf50b80 ffff81003989c4f8 ffff81003989c560 ffff810032f01000
Jul 17 17:51:14 localhost [85337.132224]  0000000000000005 ffff81003989c438 ffffffff8052d4f0 0000000500000005
Jul 17 17:51:14 localhost [85337.132229] Call Trace:
Jul 17 17:51:14 localhost [85337.132239]  [<ffffffff80265621>] generic_file_sendpage+0x2fd/0x533
Jul 17 17:51:14 localhost [85337.132249]  [<ffffffff80244670>] autoremove_wake_function+0x0/0x2e
Jul 17 17:51:14 localhost [85337.132255]  [<ffffffff802a714b>] __getblk+0x1e/0x227
Jul 17 17:51:14 localhost [85337.132263]  [<ffffffff8032a4ef>] grab_block+0x59/0xb1
Jul 17 17:51:14 localhost [85337.132267]  [<ffffffff802a711d>] __find_get_block+0x148/0x158
Jul 17 17:51:14 localhost [85337.132272]  [<ffffffff8032e0e4>] ext2_get_block+0x0/0x5d3
Jul 17 17:51:14 localhost [85337.132277]  [<ffffffff802647ee>] file_send_actor+0x31/0x4a
Jul 17 17:51:14 localhost [85337.132281]  [<ffffffff80265ec4>] do_generic_mapping_read+0x224/0x4f7
Jul 17 17:51:14 localhost [85337.132286]  [<ffffffff802647bd>] file_send_actor+0x0/0x4a
Jul 17 17:51:14 localhost [85337.132293]  [<ffffffff802661de>] generic_file_sendfile+0x47/0x5a
Jul 17 17:51:14 localhost [85337.132298]  [<ffffffff80287d82>] vfs_sendfile+0x124/0x173
Jul 17 17:51:14 localhost [85337.132303]  [<ffffffff80291f2a>] cow_break_link+0x1c6/0x26d
Jul 17 17:51:14 localhost [85337.132311]  [<ffffffff8029c6e3>] mntput_no_expire+0x1f/0x88
Jul 17 17:51:14 localhost [85337.132316]  [<ffffffff80299498>] d_path+0x10d/0x11d
Jul 17 17:51:14 localhost [85337.132320]  [<ffffffff8028679c>] sys_fchmodat+0xc4/0x1af
Jul 17 17:51:14 localhost [85337.132331]  [<ffffffff80505a7d>] error_exit+0x0/0x84
Jul 17 17:51:14 localhost [85337.132335]  [<ffffffff8020949e>] system_call+0x7e/0x83
Jul 17 17:51:14 localhost [85337.132339] 
Jul 17 17:51:14 localhost [85337.132340] 
Jul 17 17:51:14 localhost [85337.132341] Code:  Bad RIP value.
Jul 17 17:51:14 localhost [85337.132344] RIP  [<0000000000000000>]
Jul 17 17:51:14 localhost [85337.132347]  RSP <ffff8100078db910>
Jul 17 17:51:14 localhost [85337.132349] CR2: 0000000000000000