The program hangs on;

 

Step 2 : Building mesh for tile +69+018 : 
--------

-> Loading of elevation data.
-> Start of the mesh algorithm Triangle4XP :

..nothing more happens. Any clue as to what I am doing wrong?

 

You might get a better response by posting this in the Ortho4XP thread on the org. The creator of the program helps a lot there.

 

Did you try a different tile to see if that goes okay? Might be something in the tile that is not quite correct.