Problem with showing pictures

Hello,

The last week I have a problem with showing my pictures on my website. As you can see, I have many photo’s to show and I use Nextgen. Problem is that sometimes the picture is shown as a Lightbox, and that is right. See below.

But sometimes the same picture on the same device and the same browser is shown as a webpage, and that isn’t right. See below.

It doesn’t matter what device I use, the problem is at my iMac (in Safari and Firefox), iPad, iPhone and on a Windowsbased laptop using IE.

So, what’s going on and how can I repair this.

Thanks for your help and support.