In tip 0466, we saw that we could change the HAL, without running setup.
Don't try that in Windows 2000, when switching to an ACPI HAL.
To switch to an ACPI HAL, you must run Winnt32.exe to perform an update install of your current installation.
The ACPI HAL enumerates hardware differently than a standard APM HAL. The registry structure of the hardware tree must match this enumeratrion. If it doesn't, your installation will be unstable.
You may wish to read:
Q216573 - How Windows 2000 Determines ACPI Compatibility.
Q197055 - Disabling ACPI Support in BIOS Results in Error Message.