Hey guys and gals.

So for some reason Guests are able to "start topics" in forums that I've already set permissions for and Guests only (according to the permissions mask in ACP) have permission to view the forum and read threads. How do I completely disable/disallow Guests from starting threads in forums?

Are they an actual "guest" who is posting or are you using Post Before Register? Post Before Register will allow the guest to post and then have to register before the post becomes available.

You can find Post Before Register setting in ACP -> System -> Posting -> Post Before Registering