Themes and Plugins page redirects to homepage

Hello, I find this experience very weird, a friend of mine have a WP 3.7 installed on his server, he asked me some help because he is encountering some errors. If I try to change the theme or activating a plugin, when going to wp-admin/themes.php and wp-admin/plugins.php it would redirect to the homepage, if using a pretty permalinks a 404 error would show. I managed to find the cause of the error, I downgrade the installation to 3.6.1 and upgrade it via update core then it works, but if the themes both 2013 and 2012 were updated as well the error will again occur, even installing additional theme it would still occur.

Troubleshooting done:
Fresh reinstallation of WP
No plugins or any other themes installed but still I renamed the plugins folder.
I thought it was caused by the theme (but its not since on other installation it works just fine)

This is really weird, I can’t think of any other reason, I doubt that it could be the server because he got other WP sites there that works great.