Avatar Head Error

[Plymouth]

I'm running Vizard 2.5 and the models work fine in PeopleMaker. Although loading the default male and female avatars works fine I hadn't tried adding a new head that came with vizard, so I just tried sticking morph_head.vzf onto it, with very odd results. I loaded the world without any kind of trackers running and while the head shows up fine, it doesn't stay on the avatar's shoulders. The head actually moves depnding on where you're viewing it from. If I look at the avatar from a few feet away it looks fine, but if I move towards it then the head slides to the left and slides the opposite direction if I move backwards.
Also, although the image was fine on the screen, the image in the headmount was very strange. The image for the left eye worked fine, but the image for the right eye didn't contain the head at all and the image was jumping around (it looked like maybe it was switching between the left and right eye views, but I can't be sure). I then noticed that this headmount problem only occurred if I turned my head to the left to see the head. If I brought it into view from any other angle there were no problems. So I then switched te head to villain.vzf if there was a similar condition o the freezing, but alas the computer froze as soon as the head was about to come into view, although I was turning my head to the right to see it.

Is it possible that the Z800 HMD is causing the problem? I know it's a somewhat non-standard piece of equipment. For some of these trials I disabled it through Windows though.