Comment 19 for bug 307645

I am trying to apply the acpi=off solution mentioned here but am unable to change my boot.cfg file. I booted from an Ubuntu 9.04 LiveCD - accessed my laptops drive where Helena is installed and navigated to the boot/grub folder. I then right clicked on the boot.cfg file and took the option to supply a command - here I entered sudo gedit. It opened boot.cfg o.k. - I made change - I went to save [option was available i.e. not greyed out as it would be when trying to edit the real file on a loaded system] but it failed with a permissions error. Note that even though I'd used sudo I was not prompted for a password. Could someone please explain the necessary steps to make this change. Thanks, Phil