I have tried to clear the cache, manually and with the web developer toolbar.
I have tried to replace wp-config
I have set WPLANG
I have deleted everything in wp-includes/js/
I have removed the htaccess file
I have disabled all plugins, including Akismet
There is no tiny_mce_gzip.php, in the 2.5.x+ but as a test I uploaded a the file from 2.3.3 with no difference.
I have had this problem since 2.5.x and nothing makes it go away.
The most information I have is tiny_mce_config.php results in a 404 error, as do all php files in the /wp-includes/js/tinymce/ directory, although they exist when checking by FTP and it should be said that all other extensions (.css, .js, .htm) display without a 404. Permissions are the same on all files.
Any help? It's been a long time with this issue and my hope for 2.7 did not bear fruit.