Sam, the CR tech guy fixed it.
It was not something simple like cleaning up the database, but he eventually figured it out. It turned out to be a combination of bugs in the forum firmware (upgraded to latest version now), and limitations on the size of pages. My allowing 10 large thumbnails probably is responsible for exceeded the memory settings on pages, so he figured that out and overrode the settings to allow for larger pages.
Kudos for finding and fixing that!