I had the same problems even with the latest WP version.
Eventually I observed that my web-server would not server the file
tiny_mce_config.php (document not found) yet other files in the same directory were visible. (Ownership and permissions were all the same.)
The only difference I could see was that the file had a longer name than any of the others! I renamed the tiny_mce_config.php to t_m_conf.php to see if the file would behave. Sure enough it did!
So I searched for the tiny_mce_config.php references in all the php files and found just one occurrence in each of
wp-admin/gears-manifest.php and wp-includes/script-loader.php so that these could be changed to the new filename – a total of two minor edits!
Job done. Everything now works as it should. So it looks as if it may be a long filename problem on some web-server implementations.
I hope this may help someone else avoid the long journey through all the posts that have gone before.
