RoundCube|Mail : ERROR 500

Warning: include_once(config/main.inc.php) [function.include-once]: failed to open stream: No such file or directory in /var/www/localhost/htdocs/trunk/roundcubemail/program/include/main.inc on line 110

Warning: include_once() [function.include]: Failed opening 'config/main.inc.php' for inclusion (include_path='/var/www/localhost/htdocs/trunk/roundcubemail/:/var/www/localhost/htdocs/trunk/roundcubemail/program:/var/www/localhost/htdocs/trunk/roundcubemail/program/lib:.:/usr/share/php5:/usr/share/php') in /var/www/localhost/htdocs/trunk/roundcubemail/program/include/main.inc on line 110

Warning: include_once(config/db.inc.php) [function.include-once]: failed to open stream: No such file or directory in /var/www/localhost/htdocs/trunk/roundcubemail/program/include/main.inc on line 119

Warning: include_once() [function.include]: Failed opening 'config/db.inc.php' for inclusion (include_path='/var/www/localhost/htdocs/trunk/roundcubemail/:/var/www/localhost/htdocs/trunk/roundcubemail/program:/var/www/localhost/htdocs/trunk/roundcubemail/program/lib:.:/usr/share/php5:/usr/share/php') in /var/www/localhost/htdocs/trunk/roundcubemail/program/include/main.inc on line 119

Warning: array_merge() [function.array-merge]: Argument #2 is not an array in /var/www/localhost/htdocs/trunk/roundcubemail/program/include/main.inc on line 120
RoundCube|Mail : ERROR 500

DATABASE ERROR: CONNECTION FAILED!

Unable to connect to the database!
Please contact your server-administrator.