[Plugin: NextGEN Gallery] Image Upload Fails – No Error Message

I have set up the Nextgen Plugin on my website and I am able to upload images and galleries no problem. I have created an admin account for my brother to do the same thing, but images will not upload for him. When he selects the images to upload they go through the initial process, but he doesn’t get the pop-status bar or the thumbnail status bar when he clicks “upload”. He has tried uploading multiple and individual images and neither seem to go through.

I am not sure why it works fine for my admin account, but not for his. Does anyone know if it is WordPress setting issue or a setting issue on his individual Mac.

Any help would be greatly appreciated.

Thanks!

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