We’ve been bombarded by a vast number of failed log-in attempts recently (over 200 in the last 24 hours).
These have all been against a specific User ID taken from the “Posted by” links that appear under each post or comment.
Because of this I’ve had to disable that information for Users that aren’t logged into the site.
So, you will have to register and log in before you can see who’s posted something.
It’s something you have to do anyway to comment.
Sorry if this causes any inconvenience but the only alternative is to take away the ability for people to create accounts.