Hello guys,
I post this even though i finally solved the issue, because i couldn´t find any help on this topic when i was searching for this.
My problem was related to: Search (after i clicked on search, nothing appeared. Only going through the complete path i was able to reach the search form) and Sitemaps (my gsitemap was being created without WWW prefix, being that i wanted it WITH this prefix, and there is no option in the settings page about it).
The problem was that i had setup my .htaccess file so that every time someone entered http://emprender-online.com.ar, was automatically redirected to http://www.emprender-online.com.ar. The problem was that this wasn´t stated in the SETTINGS.PHP file, where my site was supposedly at http://emprender-online.com.ar. This is why the sitemap was being created without the prefix i wanted.
The search issue was related to this, because when you search, you are using a form and passing through POST variables to the next page. If the server transforms the destination URL in the form, adding a www prefix, it destroys the variables that were sent. That´s why every time i tried to search using the form, i bet the form was being sent to a url without the www prefix and thus, when it was converted, lost my particular search string.
Well, obviously, the solutions lies in the settings.php file.