Flickering textures and black outlines of characters

[Hoyty]

After some ghetto workmanship with the Underfoot client I finally got into the server. But all I can see of character models are black outlines of where the character should be and what they are shaped like. And at first I saw only grey flickering textures for the scenery/world, then I turned off advanced lighting and I could see the world but only when I look at certain angles.

Any tips on how to resolve?
System Info that may be relevant:
Intel Core I7
Nvidia GeForce 460 video card

Cheers, and thanks in advance
Hoyty

EDIT:
It seems camping out resolved the flickering textures but the character issue remains.