Hi,
I'm not sure it's connected with template, because template don't manage links from menu - Joomla does.
If you change template to default Joomla - probably you would still have problem with this.
As I see some articles have been deleted or you have "problems?" with adding a new items to menu, that's why.
If your menu items have URL with date like this:
http://www.regioncolombia.com/nueva/index.php/2013-01-09-07-19-23#
- its means that you didn't add article title and alias was generated automatically by Joomla itself.
Nobody has this same problem like you before. I suggest to read more about Joomla Menu Manger in books etc. Relax I know Joomla 3.1 is not so easy.
TIPNext time I suggest to: Install empty(no demo data) Joomla then install our template
and on another folder install quickstart to see how it works and work on this empty joomla, not quickstart.