Lightbox issues

If I reload my homepage e.g. by clicking the banner in the left corner Lightbox doesn’t work – it’s as though it’s not enabled as the photos display full screen and you have to hit the back button. If I then press F5 Lightbox works but as soon as I use a link for my home page the problem returns. I’ve recreated this in FF which I use all the time but also it happens the same in IE too.

https://wordpress.org/plugins/flickr-photostream/