I posted a comment related to this issue : https://bugs.launchpad.net/ubuntu/+source/acpi-support/+bug/74394/comments/5
I'm not an expert but I think that the problem is in power.sh : it doesn't make the difference whether or not laptop-mode is installed (and enabled on ac or battery) and overwrite the hdparm settings.
I posted a comment related to this issue : /bugs.launchpad .net/ubuntu/ +source/ acpi-support/ +bug/74394/ comments/ 5
https:/
I'm not an expert but I think that the problem is in power.sh : it doesn't make the difference whether or not laptop-mode is installed (and enabled on ac or battery) and overwrite the hdparm settings.