Getting ACPI to work is very tricky with some motherboards. When I had a problem with my shutdown this is what I did:
Downloadeded the kernel source from kernel.org
patched it with Len Browns acpi patches available here: ftp://ftp.kernel.org/pub/linux/kerne...tches/release/
rebuild it and updated my bootup
booted the new kernel
Now rebuilding the linux kernel is no easy task for a newbie so maybe in your case I would reccomend trying a diferent distibution or just accepting it.