Okay, so I have spotted one problem with my setup:
Whichever version I load of the yafaray renderer, the libraries only says yafaray 1.3 beta. This beta version is not among my downloaded files, so I have no idea where it has come from.

Now I have deleted all instances of SH3D and everything from the libraries, and reinstalled SH3D v 6.3.
With my configuration, Yafaray v 1.3 does not work. All the other versions work.

Xiste