I don't know whether you still support Joomla 2.5:
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Here is an example of Ari Sexy Lightbox which worked fine (lightbox popped up, etc) until recently:
www.hps-norfolkandsuffolk.org.uk/
4th article down (Visit to Cobb's Hall) has an Ari Sexy Lightbox module - if you view the article on its own (click on the title), the slide show works as it should.
But if you try the slide show on the original front page it does not.
The thing that stops it working is if a picture in one of the articles above it is resized - ie. it appears in the html page with width and height set, as the page in the second article is.
If I give the pic a style of max-width:100%; (the first article) it does not cause the problem and the lightboxes on the same page work, or if the pic is shown without specifying width and height (the pic in the third article) that does not cause the problem either.
Hope this is intelligible!
Any help would be gratefully received.
Thanks,
Richard