Hi Ralph,

this is the 2.x forum! As everybody knows by now, your forum is powered b Alex' 1.7x scripts. Your questions should go the respective forum, please!
The red icons/arrows are tagging posts as new (i.e., unread) for a particular user.
As far as I know, the state of the post (read/unread) is stored in a cookie in the browser's cache.
Therefore even for a registered user these red icons/arrows may be present or not if different browsers are used to view the forum.