Internal server error

-- url of the page with the problem -- : www.urbanoutlet.it/abbigliamento-firmato-siena/
-- HikaShop version -- : essential 2.2.3
-- Joomla version -- : 2.5.17
-- PHP version -- : 5.3.25
-- Browser(s) name and version -- : all of them
-- Error-message(debug-mod must be tuned on) -- : INTERNAL SERVER ERROR

I get this error when I click on the CATEGORIES PAGE and during registration. If I click RELOAD it works, though. ANy idea?

Lucia

Look in the PHP error log file of your web server in order to locate the "fatal error" responsible for that internal server error and that will give more information on why you get that.

Mon Jan 20 17:34:50 2014] [error] [client 95.235.189.206] Premature end of script headers: index.php, referer:

Lucia

This is the apache error log, not the PHP error log. Please ask your hosting company if you don't know where to find it.