WP 3.5.1 admin ajax not working properly

Hi All,

On many of my 3.5.1 sites the admin stopped working correctly a little while ago. For example moving menus around didn't work anymore. I don't know the reason but the solution is adding one line to your wp-config.php:

/* Make Ajax in admin work */
define( 'CONCATENATE_SCRIPTS', false );

/* That's all, stop editing! Happy blogging. */

Hope this hint helps someone!