Hello,
Good news! Cais has fixed my problem:
>> It appears this it was most likely a caching issue (“ensure the cache is completely cleared after every single change, no matter how minor or you may not actually see anything on the site … or the caching could actually break things (or make them look broken)”) and possibly a plugin conflict with “Easy Fancybox”.
>> What he did: updating the NextGEN Gallery to 2.0.40 (and also installing and used the NextGEN Reset Tool found under Tools > NextGEN Gallery Reset).
>> Tip when using version 2.0.40: use the ATP (attach to post) rather than a shortcode to insert a gallery.
Hope that helps and thanks again Cais.