when shutting down the computer from X, it doesn't auto power-off anymore at the end of the shuting down process.
Was perfectly working until this kernel update.
I didn't notice any power-down problems with the new kernel. But then again, I am using a pre-2001 motherboard, so I have to use "acpi=force" as a start-up parameter. Try using "acpi=force" and see whether that restores your power-down. I agree that if you're using a more modern motherboard, you shouldn't have to do that. But it might give a better clue to what, if anything, is missing from the new kernel.
Temlakos