http://support.microsoft.com/?id=309283

Windows XP Device Manager and Windows Server 2003 Device Manager list limited choices for changing your HAL type when you click Update Driver. Microsoft Windows 2000 Device Manager lets you select any HAL type. If you select an incorrect HAL, you may not be able to start Windows 2000, or you may have other issues.Although the selections are now limited, you should change the HAL only if you are sure that the selected HAL works on your system. The options that are presented here are known to be compatible with most systems. However, a few systems may experience problems.


Higlight 'My Computer'
use ALT Enter or right click select
Properties
Select the Hardware tab
Click the 'Device Manager' button
Open the Computer object
The HAL type will be shown, probably 'Standard PC'
if the installed driver says Advanced Configuration and Power Interface ACPI PC
Then the driver was not changed when you disabled it.
Right click on the Computer type and select Properties
Select the 'Driver' tab
Click 'Update Driver'
The Device Driver Update will start. Click Next
You can now either ask it to find a driver
or manually select it.

If you select Manual select
'Show all hardware' and select the ACPI driver.
Click Next
Click Next to install the driver
Click Finish and then click Close
Clicking Yes will restart your computer

If you choose wrong you may reboot to
a stop 0x0000007