Hi Paco,
I think the issue here is a slight server misconfiguration. It seems that your server is sending back JavaScript and CSS files as the mime type "text/html". Here are some examples:
> curl -i http://www.pro-evolution.com.ar/tubepress_pro_2_2_9/env/pro/tubepress-pro.php/sys/ui/static/js/tubepress.js
HTTP/1.1 200 OK
Connection: close
Date: Tue, 21 Feb 2012 03:42:02 GMT
Server: Microsoft-IIS/6.0
X-Powered-By: PleskWin
X-Powered-By: ASP.NET
X-Powered-By: PHP/5.2.5
Content-type: text/html
> curl -i http://www.pro-evolution.com.ar/tubepress_pro_2_2_9/env/pro/tubepress-pro.php/sys/ui/themes/default/style.css
HTTP/1.1 200 OK
Connection: close
Date: Tue, 21 Feb 2012 03:42:52 GMT
Server: Microsoft-IIS/6.0
X-Powered-By: PleskWin
X-Powered-By: ASP.NET
X-Powered-By: PHP/5.2.5
Content-type: text/html
Notice the "Content-type: text/html" header. This is, in effect, causing web browsers to treat the content as plain HTML and not as CSS or JS. Your server administrator or hosting provider will be able to assist you with this. I would point them to this thread if they need more details.
Sound good? Let us know what you find. Thanks!