When HOrde is installed, its Config.php is not set up correctly.
This file can be found in config/config.php under the horde folder.
The installation goes fine, when i try to access the page for horde http://www.something.com/horde i get the error
Required 'charset' not specified in DataTree SQL configuration. The file /config/conf.php should contain a $conf['storage']['params']['charset'] setting.
Details have been logged for the administrator.
Here is a link to the horde Test Page.