Vanishing/reappearing alpha textures on objects

I take a cube, hollow it out (95%) and cut paths on both ends so I have a corner of a building and the path cut edges are at right angle so I can touch them with other prims and have a clean seam. I apply the texture with windows (alpha file) inside and outside so you can see through the windows of the cube from the inside and outside of this corner piece.

Here’s what I don't understand. When I fly by some of these textured walls and look at them from an angle they disappear and you can see into the building, but when you get in front of the surface (right angle) the texture surface reappears and the walls appear normal and properly formed.

Does anybody now what this is, what causes it, how to stop it, and what it is called?
Thanks.

This sounds like it's related to the ongoing alpha sort order problem in SL's graphic engine.

Unfortunately, the fix lies totally in the hands of the Lindens. There's not much we can do about it at this point other than try and avoid overlapping transparency maps whenever possible.

Very helpful.

For clarification, it's not just SL's graphics engine, it's OpenGL. All 3D applications have alpha sorting issues. To avoid the problem, make sure you never have 32-bit-textured surfaces overlap in close proximity.