Macbook Pro - Natty Alpha 2 - System won't start with ACPI enabled

Binary package hint: acpi

When launching Natty Alpha 2 on my MacBook Pro, it crashes all the time with ACPI enabled. In order for it to launch I have to pass "acpi=off" to the kernel parameters. The problem is that this way I cannot pass "acpi_apic_instance=2" to make use of my Intel Duo Core CPU.

Description: Ubuntu natty (development branch)
Release: 11.04

acpi:
  Installed: (none)
  Candidate: 1.5-2
  Version table:
     1.5-2 0
        500 http://archive.ubuntu.com/ubuntu/ natty/universe amd64 Packages

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: acpi (not installed)
ProcVersionSignature: Ubuntu 2.6.38-3.30-generic 2.6.38-rc4
Uname: Linux 2.6.38-3-generic x86_64
NonfreeKernelModules: wl
Architecture: amd64
Date: Fri Feb 11 23:14:00 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64+mac (20110210)
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.UTF-8
 LC_MESSAGES=en_US.utf8
 SHELL=/bin/bash
SourcePackage: acpi