I'm having a very strange problem with the commenting function...I'm fairly certain that it did not exist before, and I have not made any changes such as upgrades or adding new plugins.
If a person is a registered User, as all of my Authors/Contributors/Editors are, WordPress seems to (now) be requiring that they be logged in to comment - if they are not logged in, but just fill in the Name/Email/URL fields, they get presented with a blank screen when they click on "Submit" to post their comment.
I have spent days searching, and tried all of the solutions others said worked for them......here's what I tried and eliminated as culprits:
1. I made sure my Settings>Discussion> "Users must be registered and logged in to comment " is UNchecked;
2. Optimized, repaired, dropped and re-added the wp_comments table;
3. Repaired my database;
4. Double-checked the /wp-includes/comment.php, /wp-comments-post.php, and my theme's comments.php files to be sure all the suggestions having to do with mods there were incorporated (they were, I didn't need to make any changes).
As mentioned, this has not been a problem before, but for some reason now WP seems to check the commenter's email, and if it belongs to a registered user, they must log in to comment or they get the blank screen.
Anyone have any experience with this? I'd really like to change this behaviour as I don't want to force anyone - registered or not - to log in to comment.