Thus wrote Nils Faerber:
> acpi_power-0363 [446] acpi_power_transition : Error transitioning device
> [CFAN] to D3 acpi_bus-0496 [445] acpi_bus_set_power    : Error
> transitioning device [CFAN] to D3 acpi_thermal-0567 [444]
> acpi_thermal_active   : Unable to turn cooling device [c159f1a8] 'off'

Yep, I confirm. This happens when cooling is passive. When it is active,
echoing 1 to the CFAN/state gives an oops (attached), and the whole ACPI
subsystem screws up (i.e. processes defunct when writing). I'm using 
2.4.20-acpi-20021212.

> Next I found that the thermal management seems a little strange.
> It does a pretty nice job controlling the CPU temperature using the CPU
> throtteling. But the performance settings are used in the wrong way.
> When my CPU gets hotter the performance setting is (re)set to maximum
> performance and all manual resetting it is reverted after some seconds.

Thanks for tracking it down. Indeed, when cooling mode is set to passive
and CPU intensive tasks are run, the performance setting is switched back
to P0. This does not (to my knowledge) happen, when cooling mode is active.
Strangely, this is the only time the ACPI subsystem notices change in
processor performance. Oh, and BTW: P4-M should support C3 state? If it
says it doesn't, should I [bf]lame the manufacturer?
Best regards,

-- 
Karol 'sziwan' Kozimor
sziwan-DETuoxkZsSqrDJvtcaxF/A@public.gmane.org