A good place to ask questions and advice about web development is at the mozillaZine Web Development/Standards Evangelism forum.

The helpers at that forum are more knowledgeable about web development issues.

You need to register at the mozillaZine forum site in order to post at that forum.

See http://forums.mozillazine.org/viewforum.php?f=25

I found something, but it is a little weird. The error caused by Ad Block Plus extension, but...

The subdomain name looks like: http://ad.somedomain.tld/. Maybe somewhere the http://ad.* is blocked by ABP.

The interesting thing is: For CSS and JS I used same server, same service (just add subdomain as a new virtual host). In this case the link is: http://css.ad.somedomain.tld/ for CSS, and for JS I'm using http://js.ad.somedomain.tld.

I'm not understanding why it works on http://css.ad.* and http://js.ad.* and why is not working if I use the http://ad.* because the main site (http://ad..../admin.html) is downloaded and the xhtml code appearing in the browser well.

Update: I found the filter. It's on the group "EasyList (USA)" The filter is: |http://ad.$~object_subrequest,domain=~europa.eu|~gogopin.com|~sjsu.edu|~uitm.edu.my|~uni-freiburg.de But it hasn't explained why not blocked the *.html and *.php too for the sites wich use domain http://ad.*/*.html

if the js-files are on differents subdomains but on the same domain like: http://JSsubdomain.domain.com http://HTMLsubdomain.domain.com

just add in to your js-files: document.domain = "domain.com";

Thank you for everybody. I have found the solution.

I disabled a filter in AdBlockPlus, which blocked the site starting with http://ad.*