I'm using ISPConfig to setup all the websites on my server but I also like to try to fiddle with the files myself to see how it works.

Like you guessed, yes, I've broken something. I can't access my webmail setup by default on the server with the alias /webmail (I access it via the http://xxx.xxx.xx.xx/webmail)

Firefox tells me that

The page isn't redirecting properly

      Firefox has detected that the server is redirecting the request for this address in a way that will never complete.

So I cleaned up my vhost files and the one of my websites work as intended, I think that the problem comes from my default.vhost. Here's the content of it

<Directory /var/www/>
    AllowOverride None
    Order Deny,Allow
    Deny from all
</Directory>

<VirtualHost *:80>
DocumentRoot /var/www/

    ServerAdmin [email protected]

    <Directory /var/www/>
        Options FollowSymLinks
        AllowOverride All
        Order allow,deny
        Allow from all

</Directory>
</VirtualHost>

This isn't a lot and I can't really see what's wrong with it, all I know is that it isn't the one that came with ISPConfig and I can't find an original one. Here's the roundcube.conf that loads with apache

# Those aliases do not work properly with several hosts on your apache server
# Uncomment them to use it or adapt them to your configuration
#    Alias /roundcube/program/js/tiny_mce/ /usr/share/tinymce/www/
#    Alias /roundcube /var/lib/roundcube

Alias /webmail /var/lib/roundcube/

# Access to tinymce files
<Directory "/usr/share/tinymce/www/">
      Options Indexes MultiViews FollowSymLinks
      AllowOverride None
      Order allow,deny
      allow from all
</Directory>

<Directory /var/lib/roundcube/>
  Options +FollowSymLinks
  # This is needed to parse /var/lib/roundcube/.htaccess. See its
  # content before setting AllowOverride to None.
  AllowOverride All
  order allow,deny
  allow from all
</Directory>

# Protecting basic directories:
<Directory /var/lib/roundcube/config>
        Options -FollowSymLinks
        AllowOverride None
</Directory>

<Directory /var/lib/roundcube/temp>
        Options -FollowSymLinks
        AllowOverride None
        Order allow,deny
        Deny from all
</Directory>

<Directory /var/lib/roundcube/logs>
        Options -FollowSymLinks
        AllowOverride None
        Order allow,deny
        Deny from all
</Directory>

I didn't touch that file, but I guess it has something to do with the problem. I just can't find why it doesn't work.

EDIT:

This is the errors in my apache's log

[21/Jun/2013:21:10:54 +0200] "GET /webmail/ HTTP/1.1" 302 540 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0"
[21/Jun/2013:21:10:54 +0200] "GET /webmail/ HTTP/1.1" 302 475 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0"
[21/Jun/2013:21:10:54 +0200] "GET /webmail/ HTTP/1.1" 302 475 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0"
[21/Jun/2013:21:10:54 +0200] "GET /webmail/ HTTP/1.1" 302 475 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0"
[21/Jun/2013:21:10:54 +0200] "GET /webmail/ HTTP/1.1" 302 475 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0"
[21/Jun/2013:21:10:54 +0200] "GET /webmail/ HTTP/1.1" 302 475 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0"
[21/Jun/2013:21:10:54 +0200] "GET /webmail/ HTTP/1.1" 302 475 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0"