Right, solved it.
I remmed out the lines for the multi textures, and instead just used one of them, and then changed sizeof(vertex) on the setstreamsource to sizeof(texTri), because i'm not using the vertex struct anymore. Renders fine (well, except it's still z-up, but that's 3dsmax for you).
I guess my method of using multitextures is wrong. I'll figure out another way. Sorry to have bothered you with such a simple mistake... really didn't see it =/