Following this official Ubuntu documentation page and the steps outlined under "Creating the grub2 Menuentry - grml-rescueboot", I tried to add an i386 desktop iso of the old Feisty Fawn (7.04) to the entries already present (Windows 7, and Ubuntu 12.04).

Upon reboot, the entry appears fine at the end of the menu list options; but upon clicking it, the computer goes busy briefly, then goes back to the menu.

Any ideas? I don't think it's because of the age of the distro as it should run fine on my netbook (no UEFI, etc.). Did I miss a needed step except for steps 1-3 outlined in the article?

If this cannot be remedied: Is there another way of adding an iso to the grub2 menu - without having to manually create a grub2 menuentry which I'd rather avoid?