When running:
sudo /sbin/ldconfig
the following error appears:
/sbin/ldconfig: /usr/local/lib/ is not a symbolic li
Solved, at least at the point of the question.
I searched in the web before asking, an there were no conclusive solution, the reason why this error is: lib1.so and lib2.so are not OK, very probably where not compiled for a 64 PC, but for a 32 bits machine otherwise lib3.so is a 64 bits lib. At least that is my hipothesis.
VERY unfortunately ldconfig doesn't give a clean error message informing that it could not load the library, it only pumps:
ldconfig: /folder_where_the_wicked_lib_is/ is not a symbolic link
I solved this when I removed the libs not found by ldd over the binary. Now it's easier that I know where lies the problem.
My ld version: GNU ld version 2.20.51, and I don't know if a most recent version has a better message for its users.
Thanks.