I've just installed x86_64 Lucid on a Lenovo Thinkpad X100e. On mains power it works fine but when I either switch to battery or attempt to boot on battery it hangs.

I understand the general principle of ACPI but I'm unsure how to go about diagnosing the problem.

I guess the starting point would be to completely disable everything that happens when the power state changes and verify that it doesn't then hang.

I'm not going to file a bug until I've characterized the problem - but some help with how to get started with an investigation would be greatly appreciated.