Hi Opajaap:
I changed the debug to true, went through plugins, deactivated/reactivated them all and isolated plugins that were generating error and warning messages. All of them that caused errors don't have updates to 3.5 available so they have been deleted, and some replaced. One in particular, Quick Cache, was a plugin I liked a lot for caching, but it isn't updated for 3.5 and it generates messages, so I deleted it. I downloaded WP Super Cache since you note that WPPA supports it and my site is no longer generating any error/warning messages - debug is still set to "true".
But WPPA admin still doesn't finish loading. That is, if I select a photo album to edit, it won't load past the initial section (shows Name, description, Sort order and parent album).
I had a copy of the wppa stylesheet with some slight changes loaded with my theme and read on your site that I need to remove and replace it. I've removed it, but removing it didn't fix the problem. I went ahead and replaced it and then some of the photos in the parent albums wouldn't load (on the actual site pages, not in the admin), so I took it back out again and they reappeared. There are a few styles I really NEED to be able to change, but that's a separate problem.
I can't figure out what to do further to troubleshoot this. I mean, the existing albums are loading and showing up from the outside but I can't edit them in the admin.
It isn't a capacity issue is it? We have over 400 albums and over 4,000 photos...?