Problem while viewing the photos in the album

Hi, folks!

Could you please take a short look at my albums: https://www.sundermannschule.de/fotos/schuljahr-2013-2014/

Everytime when I click on the photo, it gets dark and I can’t go forward ?? It seems like I would stuck inside of jQuery viewing or something. This problem is with photos in all albums.
I tried to deactivate all plugins but this didn’t word for me. I have the newest version of WordPress installed.

Thanks a lot in advance!

https://www.ads-software.com/plugins/nextcellent-gallery-nextgen-legacy/