Originally Posted by till
This means that you added some apache rewrite rules or redirects that cause a infinite loop.
it seems like apache is not using the default location.
in case you've a virtual host directive make sure it includes "AllowOverride All" and note "AllowOverride None"
step by step use this commands:
1) a2enmod rewrite
for clean url
2) vi /etc/apache2/sites-enabled/default/yoursite
change "AllowOverride None" to "AllowOverride All"
3) /etc/init.d/apache2 restart
4) think about backup of your config files before you get to work
hope this will help