Fixing the normals with the vertex modifier?

I don't really get how this program recalculate the normals. I've made this building from scratch (from a cube) cloning and welding surfaces, so that in the end the normals were all messed up. I selected the whole thing and used the recalculate funcion. That's the result:

The Vertex Modifier don't allow direct normal editing, but i've found a way to fix the normals (by hand, one by one, and considering that this model has about 150 vertices that's not a very charming option... :\ ) in short, the question is: how the normals are recalculated? What criteria are used?

Normals can be edited by hand by selecting a single point and rotating it, but it's really hard (actually I've never really tried it, too difficult)

That's far too much work. I wouldn't mind if i had to fix 10 or even 20 vertices, but over 100... :\ it would be great if the program could allow to select a group of vertices and then select the direction of the source of light (hint hint)

This version has a newer and hopefully better normal-recalculating function. Were you selecting the vertices before you tried recalculating?

Another thing that could be wrong is you having some of the faces backwards. Copying faces really isn't the best way to make a model (extrude!).

Can you upload your MDL? If you do, I'll be able to mess around with it until it's fixed one way or another.

*Bow to lord Oinkerwinkle, who kindly allow poor guys like me to model with his freeware tools*

Here it is, i don't use the extrude function as often it seems to miss a face or two, expecially with anything more complex than a cube. And, unfortunately there seems to be a bug with the version you uploaded; recalculating the normals crash the program