Hi,
I have Lightbox Slideshow 3.2 installed on my CPG 1.5.18. When I am logged in as administrator, it works fine. However, for regular users the Lightbox does not appear. The full-size picture appears instead.
Other plug-ins listed in order on my plug-in page:
album_addfac
easy_rss
pic_download_link
keywords_add
keyboard_navigation
fav_button
del_fav
social_sharing
mobile_lite
jsmin
lightbox_notes_for_net 3.2
I have screenshots to show:
#1 -- I am logged-in as Administrator (CPG is bridged to SMF Forum)
#2 -- Lightbox works
#3 -- Two pictures to show test account logged-in
#4 -- Lightbox doesn't work
Website is universeofmen.com
Test account: test256
Password: oxdeadbeef16
Some users had reported issues with jsmin and LightBox. See the thread for that plugin for some suggestions or try removing it.
I have no experience with some of the other plugins that you list - you could also try moving the order up / down or try removing them one at a time.