One user (that I know of) had a slight problem after I upgraded the Photo Gallery software.... Each time he tried to view a photo it would pop up an error saying he needed to be registered to view photos, even though he WAS registered!!
The solution was simple, he just deleted the paddleducks cookie files so they were recreated on the next login - and voila, everything now works!
So if you experience a similar problem, logout from the forum AND the photo gallery, and try deleting your cookie files. Then login again - hopefully that should sort it.