This fragment of /var/log/messages may help: Oct 7 11:47:39 niobe kernel: [ 13.899482] nvidia 0000:01:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16 Oct 7 11:47:39 niobe kernel: [ 13.899501] vgaarb: device changed decodes: PCI:0000:01:00.0,oldd ecodes=io+mem,decodes=none:owns=io+mem Oct 7 11:47:39 niobe kernel: [ 13.899678] NVRM: loading NVIDIA UNIX x86_64 Kernel Module 260.1 9.06 Mon Sep 13 04:29:19 PDT 2010 Oct 7 11:47:40 niobe kernel: [ 14.110503] type=1400 audit(1286444860.042:12): apparmor="STATUS" operation="profile_load" name="/usr/bin/evince" pid=1014 comm="apparmor_parser" Oct 7 11:47:40 niobe kernel: [ 14.115146] type=1400 audit(1286444860.042:13): apparmor="STATUS" operation="profile_load" name="/usr/bin/evince-previewer" pid=1014 comm="apparmor_parser" Oct 7 11:47:40 niobe kernel: [ 14.118068] type=1400 audit(1286444860.042:14): apparmor="STATUS" operation="profile_load" name="/usr/bin/evince-thumbnailer" pid=1014 comm="apparmor_parser" Oct 7 11:47:40 niobe kernel: [ 14.946438] ppdev: user-space parallel port driver Oct 7 11:47:41 niobe kernel: [ 15.725989] sky2 0000:04:00.0: eth0: enabling interface Oct 7 11:47:41 niobe kernel: [ 15.726366] ADDRCONF(NETDEV_UP): eth0: link is not ready Oct 7 11:47:43 niobe kernel: [ 17.699102] sky2 0000:04:00.0: eth0: Link is up at 100 Mbps, full duplex, flow control both Oct 7 11:47:43 niobe kernel: [ 17.699386] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready Oct 7 11:47:46 niobe kernel: [ 20.252892] EXT4-fs (sda3): re-mounted. Opts: errors=remount-ro,c ommit=0 Oct 7 11:47:47 niobe kernel: [ 21.964759] PGD 11b45b067 PUD 125569067 PMD 0 Oct 7 11:47:47 niobe kernel: [ 21.964766] CPU 3 Oct 7 11:47:47 niobe kernel: [ 21.964767] Modules linked in: binfmt_misc parport_pc ppdev snd_hda_codec_nvhdmi nvidia(P) snd_hda_codec_realtek arc4 snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq snd_timer lp video snd_seq_device iwlagn intel_agp iwlcore intel_ips sony_laptop snd parport uvcvideo videodev soundcore mac80211 v4l1_compat v4l2_compat_ioctl32 snd_page_alloc cfg80211 output usbhid hid ahci firewire_ohci libahci sdhci_pci sdhci led_class firewire_core sky2 crc_itu_t Oct 7 11:47:47 niobe kernel: [ 21.964787] Oct 7 11:47:47 niobe kernel: [ 21.964789] Pid: 1250, comm: Xorg Tainted: P 2.6.35-22-generic #33-Ubuntu VAIO/VPCF12C4E Oct 7 11:47:47 niobe kernel: [ 21.964791] RIP: 0010:[<0000000000000000>] [<(null)>] (null) Oct 7 11:47:47 niobe kernel: [ 21.964793] RSP: 0018:ffff88011b4e7990 EFLAGS: 00010292 Oct 7 11:47:47 niobe kernel: [ 21.964794] RAX: 0000000000000161 RBX: ffff880126208000 RCX: 0000000000000000 Oct 7 11:47:47 niobe kernel: [ 21.964796] RDX: 0000000000000001 RSI: ffff880126208000 RDI: ffff88012686e000 Oct 7 11:47:47 niobe kernel: [ 21.964797] RBP: ffff8801268e5ef0 R08: 0000000000000000 R09: 0000000000000000 Oct 7 11:47:47 niobe kernel: [ 21.964798] R10: 0000000000000098 R11: 0000000000000001 R12: ffff88012686e000 Oct 7 11:47:47 niobe kernel: [ 21.964800] R13: ffff88012686e000 R14: 0000000000000000 R15: 0000000000000000 Oct 7 11:47:47 niobe kernel: [ 21.964802] FS: 00007f540e855840(0000) GS:ffff880001ec0000(0000) knlGS:0000000000000000 Oct 7 11:47:47 niobe kernel: [ 21.964803] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Oct 7 11:47:47 niobe kernel: [ 21.964805] CR2: 0000000000000000 CR3: 000000011b478000 CR4: 00000000000006e0 Oct 7 11:47:47 niobe kernel: [ 21.964806] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 Oct 7 11:47:47 niobe kernel: [ 21.964808] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Oct 7 11:47:47 niobe kernel: [ 21.964809] Process Xorg (pid: 1250, threadinfo ffff88011b4e6000, task ffff88011cbb2dc0) Oct 7 11:47:47 niobe kernel: [ 21.964812] ffffffffa049a089 ffff880126208000 ffff880126208000 0000000000000000 Oct 7 11:47:47 niobe kernel: [ 21.964814] <0> ffffffffa04aa9a0 0000000000000000 ffff880126208000 ffff88012686e000 Oct 7 11:47:47 niobe kernel: [ 21.964816] <0> ffff880126208000 0000000000000000 ffffffffa04a8859 ffff8801263d8000 Oct 7 11:47:47 niobe kernel: [ 21.964988] [] ? _nv021418rm+0x13/0x26 [nvidia] Oct 7 11:47:47 niobe kernel: [ 21.965105] [] ? _nv021317rm+0xf5/0x1b9 [nvidia]