If you are experiencing issues modifying articles with your TinyMCE editor through a web browser (for example Internet Explorer 9) the easiest solution will be to download the newest version of TinyMCE from http://www.tinymce.com/download/download.php and replace your old TinyMCE.

The Joomla users should extract the archive on the local computer, open the extracted directory and replace the directory plugins/editors/tinymce/ in their Joomla with the content of the tinymce directory from the archive.

The WordPress users need to extract the content of the archive directory tinymce/jscripts/tiny_mce/ in the wp-includes/js/tinymce folder.

After this they should be able to edit and save the posts and pages using TinyMCE.

It is important always to make backups of the files that you edit/delete/replace in order to make sure that you can revert any changes that may damage your website.