[Plugin: NextGEN Gallery] Problem When Clicking On Thumbnail

Hi

Using NextGen I set up my blog posts to included a few thumbnails. Originally, when I clicked on a thumbnail the screen would turn dark and the full size image of the thumbnail would appear. I could then navigate forward and back through the gallery. Suddenly this has changed. Now when I click on a thumb my browser goes to a new page and shows the image with a plain white background.

I have been doing a lot of work setting up the blog and assume that I changed something by accident in the process, but I can’t get it to revert to its original set up.

http://www.halftempotravel

Any Ideas?

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