I don't get this.

There are random errors that just appear for no reason. The edge isn't open...
That's in wireframe


This is normal


I don't see any errors...I've tried removing the edge and welding. Nothing has changed.
This is what I did:
Made a box, tesselated (is that the problem?), paint deformated to create the mountain\cliffs, manually moved some verticies and edges, welded a tiny bit, and then textured.

Also, when I try to export it using bliztkreig, 3ds crashed. I had to use bluestreak, and when I compiled, all those errors showed up.

Any ideas?