Morph gone crazy!

Okay, here I am, casually working on a character's head for a tv spot. Four types of heads- normal, and three types of smiling. The plan is to morph between heads, depending on the shot.

Great, so... I've modeled the heads accordingly. I start a new scene to test the morph. Works great. Hooray. I save the scene.

Then, without any changes to the model, the morph no longer functions correctly. Point fly off randomly and the model turns itself inside out. I've thrown out the prefs. I've restarted the computer (Macbook w/ OS 10.5.6, btw). I've restarted Lightwave. I've even created a new scene from scratch. Same problem. Try an older version of the model, you say? Did that, too. Morphs no longer function in any kind of usable manner.

Why, oh WHY?! would Lightwave do this and, more importantly, how do I fix it?