it seems that there is a bug with the lightbox addon. Depending on the size of the browser window, sometimes the images are no longer centered, they appear to move to the left if you browse through a gallery of several images. The first few look alright, but then gradually, they appear further and further off center to the left. When I adjust the window size slightly then all of a sudden they lock back into place, but at a default (full screen) window size I get that problem a lot...
Thanks for your help!
All the best,