Have you tried clearing the

Megan — Mon, 16 Dec 2013 14:43:00 +0000

Have you tried clearing the cache? Those errors indicate that Drupal can't find some Advanced Forum template files. It could be that there was an update to the module and the location of those files changed, or something like that. Either that or those files were accidentally deleted, but I think you would be having display problems on your site if that happened.