General Support: I think I made a big mistake

BryanK,

You must be using beta3 (this was a bug that is now fixed in the new version). If you deleted a thumbnail that was being used as the collection or album thumbnail, the thumbnail would not be reset for the collection or album in question. To fix for your end, just log in to Admin -> Manage and click the pencil and paper (edit) on the right hand side for the Collection or Album in question. Next, select a new thumbnail or the default Plogger setting from the pulldown list and click "Update". View your front-end gallery again and it should be fixed.