Others may disagree, but I am of the opinion that all ide chipset and hard
disc related drivers should be compiled directly into the kernel instead
of getting loaded as a module. When you load the piix module the kernel
is being asked to make some major changes to an IDE subsystem that has
already been initialized by the generic PCI IDE driver and is in use. The
kernel may balk at that and refuse to touch a busy device.
When specific IDE chipset drivers are compiled directly into the kernel
those drivers will superceed the generic driver and initialize the ide
system properly the first time around.