I had a similar problem that was reated to usb legacy suport in the BIOS. There was some discussion on another list regarding the buggy usb-legacy feature that BIOS uses.
Try going into your BIOS and disable this "feature"
I think that acpi=on is already active in non-amd64 kernels. It shouldn't hurt to pass that on the kernel boot line for safety.
This worked for me, which advice I got from another computer user. I passed the info onto someone else, who it helped. Then he passed on the advice to another user.
The symptoms sound the same as mine. I'm hoping this gets your install on the way.
Jim
-- Learn to pause -- or nothing worthwhile can catch up to you.
