APM not working with sp2

[Eddie Bellia]

I have a clean install of XP Home with SP2 installed.

With SP1 everything was fine but, now with all APM set
correctly in the BIOS and XP's power management settings
my monitor no longer goes into standby.

All help gratefully received.

 

[Andre Da Costa]

Maybe your Bios needs updating.

Andre

 

[R. McCarty]

If you did a clean install, you'll need to check Device Manager &
see which HAL (Hardware Abstraction Layer) was selected by XP
during install. If the Computer Category has an entry for Advanced
Configuration and Power Interface PC then APM isn't going to work.
ACPI is a more modern power control methodology. BIOS reports
to XP at install if the PC (Motherboard/Chipset) supports ACPI &
if told Yes, XP will load the ACPI HAL.
Sometimes if "Standard PC" (HAL) is loaded, the APM system
driver doesn't get loaded. This must be manually loaded to re-enable
proper APM support.