USB Printer fails to initialize after disabling ACPI
 

I've been working on a PC with Intel mobo D101GGC. We discovered that when ACPI is enabled, issuing a 'reboot', 'shutdown -fr', or 'init 6' caused the system to shutdown (or mostly shut down and then hang) instead of rebooting. Since we needed to be able to reboot the system remotely we disabled ACPI at boot with 'acpi=off', but after doing so the previously working USB printer no longer responds. When ACPI is enabled, the printer works fine, with ACPI off the printer doesn't work.

What is the connection between ACPI and USB? Is there any reason disabling ACPI would cause a USB device to not initialize?