Thank you for the reply.

I installed Slimbox first and then installed Lightbox over it. I am not running both. I am running Lightbox. The Slimbox is installed but disabled through the control panel. I can uninstall Slimbox, if necessary.

I do not think the issues with arrows are related to the fact that I have them both installed. First, there are no arrows, there are 'buttons' Next and Previous. (I seem to vaguely remember that the real Lightbox should have arrows). Those buttons, Next and Previous, do appear in the Internet Explore but do not appear in Firefox. I think the answer could be that the current version of Zen Lightbox is not meeting some requirements of Firefox and buttons do not appear in FF. I could be wrong, of course, and if I am, I would like to fix this issue. If anybody with Firefox has buttons fully operational, please let me know.