I needed to set my Apache Web Server to ignore/block all the HEAD requests but respond to GET requests normally. It is very simple with the mod_rewrite, for instance this can be added to .htaccess:
RewriteEngine On
RewriteCond %{REQUEST_METHOD} HEAD
RewriteRule ^.*$ - [F]
Second line:
RewriteCond %{REQUEST_METHOD} HEAD
matches all requests that use method HEAD.
Third line:
RewriteRule ^.*$ - [F]
tells Apache HTTP not to make any redirection (-) and sends back HTTP 403 (FORBIDDEN).