I've found today that this plugin breaks down in WP 3.5, specifically in the new Upload Media functionality. With it activated, I could not use the new drag-n-drop media uploader, nor could I close the media manager. Trying to drag an image into the manager just loads the jpeg in the browser window. I isolated this plugin by deactivating all my active plugins and selectively turning them back on until I reproduced the problem.
I know a lot of plugins are failing in 3.5, so there should be a patch coming soon.