[Plugin: NextGEN Gallery] WP: Can't attach Featured Image

After upgrade from 1.9.3 to last version of NGG. I can´t remove ou set post thumbnail.

Error was:
POST *website*/wp-admin/admin-ajax.php load-scripts.php:4
f.support.ajax.f.ajaxTransport.send load-scripts.php:4
f.extend.ajax load-scripts.php:4
f.each.f.(anonymous function) load-scripts.php:4
WPSetAsThumbnail load-scripts.php:6
onclick

After install a fresh install of WP and install only last NGG the problem remains.

Solution: Back to 1.9.3 version e clean cookies.

The last version sets some information in wp-settings-{userid} cookie. When I delete this cookie the problem goes.

More information on last post on:

http://css-tricks.com/forums/discussion/18750/wp-can039t-attach-featured-image

NGG does not remove all settings from WP Database after uninstall plugin. See {prefix}_usermeta table and search for wp-settings key.

http://wordpress.org/extend/plugins/nextgen-gallery/