Have you installed specific motherboard drivers or are you relying on the Vista built in drivers? If you have only installed Vista setup drivers for the the mobo try going to the manufacturers website and downloading the latest motherboard drivers.
Specific chipset-drivers from intel, and their graphics drivers and wifi drivers as well. Can't remember if the realtek gigabit LAN was Vista built-in or if I had to install specific drivers. Iirc audio is vista built-in.
Turned out that the ZeptoMobileUtilities thing did
have the ACPI driver, doh! I'm curious to see if this will fix the usb-device freeze thing, but somehow I doubt it (although there could have be some power management issue after hibernate because of missing driver, dunno).
Haven't installed the whole package though, there's no more drivers in Device Manager that are missing, and while there are other drivers in the pack, they seem to be related to battery status indicator, some specific multimedia keys (that already seem to work just fine), et cetera.