It appears that if the laptop is hot and so the fan is running when the kernel takes control, it's able to control the fan, but if the fan is not running when the kernel takes over, it never runs, the machine overheats, and shuts down.
Here's the /proc/acpi diff between when there is a fan and there is no fan. Please let me know if additional information would be helpful diff -ruN fan/acpi/processor/CPU0/power nofan/acpi/processor/CPU0/power --- fan/acpi/processor/CPU0/power 2007-09-18 16:41:08.000000000 -0400 +++ nofan/acpi/processor/CPU0/power 2007-09-18 16:08:24.000000000 -0400 @@ -1,7 +1,7 @@ active state: C2 max_cstate: C8 -bus master activity: ffffffff +bus master activity: ffc0ffff maximum allowed latency: 8000 usec states: - C1: type[C1] promotion[C2] demotion[--] latency[000] usage[00001660] duration[00000000000000000000] - *C2: type[C2] promotion[--] demotion[C1] latency[010] usage[00044141] duration[00000000000404148212] + C1: type[C1] promotion[C2] demotion[--] latency[000] usage[00007420] duration[00000000000000000000] + *C2: type[C2] promotion[--] demotion[C1] latency[010] usage[00561247] duration[00000000006395914844] ** Changed in: linux-source-2.6.22 (Ubuntu) Status: Incomplete => Triaged -- CPU fan no longer runs after upgrade to Gutsy https://bugs.launchpad.net/bugs/127772 You received this bug notification because you are a member of Ubuntu Bugs, which is the bug contact for Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs