Maybe I should leave well enough alone, but I can't resist...
First, user albums are enabled/disabled through the setting enableUserAlbum. When this setting is false, GSP puts a "0" in the setting userAlbumParentAlbumId, but it shouldn't matter because that setting should always be ignored when enabledUserAlbum="false".
Second, when you upgraded from 2.3.3421, there were two upgrade techniques:
1. Keep your existing gsp.config and paste in the new settings.
2. Rename your original file to galleryserverpro_old.config and use the upgrade wizard to import the settings.
In either case your original settings should have migrated to the new version. Did you perhaps follow a third, ahem.. undocumented upgrade path?
Roger Martin
Creator and Lead Developer of Gallery Server Pro