You can only reply to your own threads as long as your not a member, unfortunately you can't see this differentiation in the posting rules box down bottom left on the screen.briefly, i've struck a wall trying to reply to a thread or two. is this normal or are my settings off?
If you really want to reply to somebody else's thread then just start a new one and title it appropriately as (I hope) I've done.
Cheers
Roy