Cant disable ACPI on Freebsd 7/amd64 RC1

[alex]

Hi,

I want to try disabling ACPI temporarily to see whether it helps resolve 
a separate issue I am having. However when I try to disable ACPI by 
adding the necessary line to /boot/loader.conf  the system will no 
longer boot. The kernel fails with an error message for my ATA drives 
saying it was unable to allocate an IRQ for the devices.

The motherboard is a Gigabyte 945GM-S2 (with Latest BIOS revision F6). 
There is no option in the AmiBIOS setup to alter PnP OS/IRQ routing.

What can I do now?

Alex.