Last Reply by unregistered?

Why does the name ‘unregistered’ sometimes populate the last post by field? I’ve now seen it twice in GQ and once in ATMB. It seems to occure with closed or moved threads.

Nothing to do with that, it happens sometimes with the quick reply box.

Happened to me yesterday. Specifically, it happens when you use the quick reply box, hit “Submit”, and the boards have somehow logged you out in the meantime. You log in, the post is submitted, and the forum index lists you as “Unregistered”.