The WYSIWYG editors are great additions to the Joomla, and we have lots of them around. They make a webmaster from casual user and can speed up the work of pros. But, sometimes, you find that you cannot enter text into the HTML editor, or click on the HTML editor's toolbar buttons - you are locked out of editing your content!
What can be more annoying as being unable to edit your own site?
Whether or not to use "www." depends on the settings in your configuration.php file. Go to Site->Global Configuration (from the main menu in Joomla), click on the Server tab, and check the 'Live Site' setting. If the live site setting includes www. then you must use www. when accessing Joomla administrator. If live site does not include www. then you must not use www. when accessing Joomla administrator.