So I had this "beautiful" website that did exactly what I wanted it to do. Then I shut down my PC, reboot and...the pages just download now instead of being displayed.

I re-installed XAMPP and launched Apache again and I was able to identify the .htaccess file as the cause of the problem.

Options +FollowSymlinks
RewriteEngine on 

RewriteCond %{QUERY_STRING} !^desktop
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|googlebot-mobile|iemobile|iphone|ipod|#opera mobile|palmos|webos" [NC]
RewriteRule ^/?$ /mobile/index [L,R=302]    
RewriteRule ^/?$ /de/index [R]
RewriteCond %{REQUEST_FILENAME} !-d 
RewriteCond %{REQUEST_FILENAME}\.html -f 
RewriteRule ^(.*)$ $1.html

Here is the problem I guess:

RewriteCond %{REQUEST_FILENAME} !-d 
RewriteCond %{REQUEST_FILENAME}\.html -f 
RewriteRule ^(.*)$ $1.html

This should make it possible to use /de/index instead of /de/index.html - but somehow it causes the page to download if I open localhost/de/index (but with localhost/de/index.html it works fine...).

I'm using HTML Sites with SSI Elements on a Apache web server. The only other file that is different to the out-of-the-box ones is the httpd.conf, where I enabled SSI:

AddType text/html .shtml
AddHandler server-parsed .shtml
AddHandler server-parsed .html
AddHandler server-parsed .htm
Options Indexes FollowSymLinks Includes
AddOutputFilter INCLUDES .shtml
Options +Includes

So I hope there is somebody among you that can help me with this annoying problem as I'm quite desperate... for some reason, even without the problematic lines Chrome keeps downloading the files (even if I delete the .htaccess file), while IE and Opera display the pages.

Edit: Now Opera also wants to download files (whether index.html or index are called).