I'm A Banana
Potassium-Rich
Naah, the way I figger, Undead are immune to mind-affecting effects becasue those work on neurons and chemicals -- the undead ain't got those. They can't get their blood boiling, 'cuz they ain't got blood. 
Undead are created IMC by the corruption of a soul -- the soul being the manifestation of Positive Energy, of Life. This is why creating undead is Evil, but creating a Bone Golem is not.
Your mind is attatched to your soul, because a soul is required to generate a mind; a mind is basically a soul's defense mechanism, how it detects threats against it and moves to protect itself. The Body, then, is the mind's defense mechanism, how the mind influences the physical world.
When you die, your body fails, and your mind is vulnerable to the inherent energies of reality -- it is shunted off the plane, to the afterlife, with your soul, which then manufactures a new body (thus making resurrection impossible -- your body is your mind and soul). The process on your plane of death is a process of melding your mind with the plane; the plane is, in essence, all these similar minds that ever existed. The soul, then, devoid of body (material) and mind (outer), travels through the Far Realm, back to Positive Energy, where it births another physical mind and body. Which is why the Far Realm creatures are so maddening -- they don't follow the mind, because they are independant of it; they are pure soul, given body without mind.

Undead are created IMC by the corruption of a soul -- the soul being the manifestation of Positive Energy, of Life. This is why creating undead is Evil, but creating a Bone Golem is not.
Your mind is attatched to your soul, because a soul is required to generate a mind; a mind is basically a soul's defense mechanism, how it detects threats against it and moves to protect itself. The Body, then, is the mind's defense mechanism, how the mind influences the physical world.
When you die, your body fails, and your mind is vulnerable to the inherent energies of reality -- it is shunted off the plane, to the afterlife, with your soul, which then manufactures a new body (thus making resurrection impossible -- your body is your mind and soul). The process on your plane of death is a process of melding your mind with the plane; the plane is, in essence, all these similar minds that ever existed. The soul, then, devoid of body (material) and mind (outer), travels through the Far Realm, back to Positive Energy, where it births another physical mind and body. Which is why the Far Realm creatures are so maddening -- they don't follow the mind, because they are independant of it; they are pure soul, given body without mind.