ACPI problems

[Sad Clouds <cryintothebluesky%googlemail.com@localhost>]

I'm having weird problems with ACPI on NetBSD-5.0_STABLE, running on
dual Pentium 3 machine.

Running 'shutdown -p' sometimes powers off the system and sometimes it
leaves it still running.

I've noticed the following error messages in the log file:

Jan 27 11:34:23 p3smp /netbsd: ACPI Error (hwacpi-0225): Hardware did
not change modes [20080321]
Jan 27 11:34:23 p3smp /netbsd: ACPI Error (evxfevnt-0171): Could not
transition to ACPI mode [20080321]
Jan 27 11:34:23 p3smp /netbsd: ACPI Warning (utxface-0233): AcpiEnable
failed [2 0080321]
Jan 27 11:34:23 p3smp /netbsd: ACPI: unable to enable:
AE_NO_HARDWARE_RESPONSE

Any idea of this could be a hardware fault or perhaps software related
to NetBSD kernel?