I've run into that and had to call Gigabyte for affirmation or new bios (BETA!) and drivers. Some think they should put it on the web...
I am trying to upgrade (!) from XP Pro to Vista home premium. I have a Gigabyte GA-M61P-S3 motherboard, with an AMD Dual Core processor, 2 gigs of RAM. There are no current XP issues. This board and processor are new, with the latest bios and drivers from Gigabyte. When I attempt to upgrade, Vista states that my board is not ACPI compliant, and the upgrade fails. The ACPI controller, IRQ 9, is enabled, and has been functioning well under XP. Even the Vista Upgrade Advisor from Microsoft reports that there should be no issues with the install. Any clues? I don't want to do a fresh install, as this issue may remain.

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