ACPI disables USB ports on Lenovo X200

[Damian Gerow]

Brandon Gooch wrote:
: > For kicks, I just booted a kernel without any USB support at all, and
: > experience the same symptoms: the mouse is functional (well, appears to be,
: > anyhow) when the boot loader is active, but goes dark around when ACPI
: > starts to do its thing.
: 
: Damien, sorry if you've mentioned this already, but have you taken a
: look at the BIOS settings? In particular, check out "Legacy USB
: Support" options and experiment with changing the value(s)...

I've only got two USB-related options in my BIOS:

USB BIOS Support: Toggles the support for booting from USB devices
Always On USB: Toggles the power status of USB ports as they related to the
               power status of the laptop

So, no legacy USB support knob.  And yes, I've tried setting changing both
of those options, to no avail.