sudden reboot or freeze

Here is a copy of my syslog from the time I think my computer crashed.

Feb 14 23:35:46 philip-desktop kdm[3903]: X server for display :0 terminated unexpectedly
Feb 14 23:35:49 philip-desktop hcid[4144]: :1.3 exited without unregistering the default passkey agent
Feb 14 23:35:50 philip-desktop kdm: :0[6587]: IO Error in XOpenDisplay
Feb 14 23:35:50 philip-desktop kdm[3903]: Display :0 cannot be opened
Feb 14 23:35:50 philip-desktop kdm[3903]: Unable to fire up local display :0; disabling.
Feb 14 23:36:14 philip-desktop init: tty1 process (3558) killed by signal 15
Feb 14 23:36:14 philip-desktop init: tty2 process (3559) killed by signal 15
Feb 14 23:36:14 philip-desktop init: tty3 process (3560) killed by signal 15
Feb 14 23:36:14 philip-desktop init: tty4 process (3561) killed by signal 15
Feb 14 23:36:14 philip-desktop init: tty5 process (3562) killed by signal 15
Feb 14 23:36:14 philip-desktop init: tty6 process (3563) killed by signal 15
Feb 14 23:36:20 philip-desktop hcid[4144]: Got disconnected from the system message bus
Feb 14 23:36:22 philip-desktop exiting on signal 15
Feb 14 23:37:09 philip-desktop syslogd 1.4.1#18ubuntu6: restart.
Feb 14 23:37:09 philip-desktop kernel: Inspecting /boot/System.map-2.6.17-11-generic
Feb 14 23:37:09 philip-desktop kernel: Loaded 22866 symbols from /boot/System.map-2.6.17-11-generic.
Feb 14 23:37:09 philip-desktop kernel: Symbols match kernel version 2.6.17.
Feb 14 23:37:09 philip-desktop kernel: No module symbols loaded - kernel modules not enabled.
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] Linux version 2.6.17-11-generic (root@terranova) (gcc version 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)) #2 SMP Thu Feb 1 19:52:28 UTC 2007 (Ubuntu 2.6.17-11.35-generic)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-provided physical RAM map:
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-e820: 0000000000000000 - 0000000000080000 (usable)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-e820: 0000000000100000 - 000000000dfec000 (usable)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-e820: 000000000dfec000 - 000000000dfef000 (ACPI data)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-e820: 000000000dfef000 - 000000000dfff000 (reserved)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-e820: 000000000dfff000 - 000000000e000000 (ACPI NVS)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] BIOS-e820: 00000000ffff0000 - 0000000100000000 (reserved)
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] 0MB HIGHMEM available.
Feb 14 23:37:09 philip-desktop kernel: [17179569.184000] 223MB LOWMEM available.
Feb 14 23:37:09 philip-desktop ker...

See sometimes happens to me too. After deinstallting package "powernowd" it is quite better, but from time to time it happens.

Ubuntu 7.10 (in previous version 7.04 it happens too).
With or without nVIDIA driver installed. GeForce 7800 GS 512.

See attached part of syslog which might be interesting.

No activity in a long time, closing the bug. If you still can reproduce the issue on Ubuntu Hardy, please reopen. Thanks.

TheGeneral: your problem is unlikely related.