Halt (in grub) doesn't work for me either, that is, the machine is halted but not turned off. That's probably a grub bug. I have to keep the power button pressed to turn it off, but that's safe once the machine is halted and the hard drive has parked.
-- bad hard disk noise on shutdown https://launchpad.net/bugs/67810 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
