I get a very similar crash (loading ACPI modules dies at kref_get()) on my Mac Pro workstation. 2.6.20-12 did not have this problem. I upgraded all packages at once, so I have the latest ACPI support tools.
I'm back to running 2.6.20-12 with a downgraded nvidia-glx until this gets resolved. -- Kernel 2.6.20-13 acpi bug https://launchpad.net/bugs/96480 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
