On a Compaq EXD Deskpro with a Intel 815 mainboard, poweroff fails. It says that the system is halted, but doesn't power off. Seems to hang the machine, normal power switch doesn't work anymore either (pressing it for some seconds does the job as usual - this is really a hard power-off).
Poweroff fails on "Asus P2 (rev1011.A) / i440ZX" too. I see ... ... Poweroff. and it stays on. I have not the power switch problem, though; I can switch it off ok with just a quick press (no need to do a 2/3 seconds press or hard power- off).
This defect is considered MUST-FIX for Florence Gold release
Because this is APM-related, it could even be related to the BIOS versions you have. Have you checked to see if there are BIOS updates for your machines?
Did check it (and upgraded it to the latest version). Did also try this with beta2, still the same. Did some further testing - this bug does occur in 7.0, too. However, after upgrading to 2.2.19-pre1 (needed the pre1 because of some AGP related stuff) this worked. Didn't really note it right then.
This is believed to befixed by having READ_MODE_POWEROFF disabled in the config of the next Rawhide kernel we build (version 2.4.1-0.1.6 or later). If these kernels does not fix the problem for you, please reopen this bug.