Problem with ACPI

Hiho! :-)

If I try to use ACPI on my Tyan Thunder X, I get

acpi0: <AMIINT > on motherboard
    ACPI-0168: *** Error: Could not transition to ACPI mode.
acpi0: Could not enable ACPI: AE_NO_HARDWARE_RESPONSE
device_probe_and_attach: acpi0 attach returned 6


when it is probed by the kernel.

ACPI is enabled both in the bios and in the kernel (compiled in, not as
a module).

That behaviour causes no problems at all (except I can't use the ACPI
features, but I don't really miss them), but I'm curious about that
message. 

Does it indicate a problem with my board or a flakey bios? Is there some
kind of workaround?

Thanks for your help!

Bye
Marc