When accessing the admin area in joomla 2.5 you might receive a "404 component not found error" this is due to the way Joomla interprets the site url incorrectly.
You need to ensure that the $live_site variable is populated so images etc work, but when this is populated the admin area gives an error. This is currently seen in joomla 2.5.1 to 2.5.6 and might affect later versions as well.
To correct this issue please do the following once your joomla installation is completed.
1) edit the following file in the joomla root folder "/libraries/joomla/environment/uri.php"
2) scroll down to line 225, you should see the following code
if (JPATH_BASE ==JPATH_ADMINISTRATOR)
{
self::$base['path'] .= '/administrator';
}
3) change the bold code above with this bold code below
if (JPATH_BASE ==str_replace('/', '\\', JPATH_ADMINISTRATOR))
{
self::$base['path'] .= '/administrator';
}
4) Close any open browser windows, reopen the website goto the wesite url/administrator url and login, you should be working 100% ok now.
If you still have any issue please contact the support helpdesk