When are you seeing the error message? Are you attempting to install Windows 2000? Something else.
Maybe the links below will get the job done. (Note the middle of the page...Press F7 to disable):
"STOP 0x000000A5" When Installing Windows 2000
How to Troubleshoot Windows 2000 Hardware Abstraction Layer Issues
Hope this helps.
I Dont know how to disable acpi how do i disable it i have a big blue screen saying i should update bios or press f7 to diable. I have the newest bios to. So anyone know