Until you rolled out the new image handling, I never had an issue with comments being allowed on individual attached images with my Theme (Piano Black.) Now They are allowed and I don’t know how to disable it. Is it possible to do it without having to mess with the database (as was suggested in one thread I looked at)?
You can only have attachment pages with no comment box if you create the post under a no-comments-allowed default (in Settings > Discussion), then override that setting for the particular post after you publish it (post editor > Discussion module > tick “Allow comments on this post”, or Posts > Edit > Quick Edit > tick “Allow comments”). http://wpbtips.wordpress.com/2009/04/26/images-the-three-link-options/