If the Tularean castle is locked as well, what might have happened is what happened to me. I was exploring the Tularean Caves, and I found a passage. I went through the door at the end to see where it went, and found myself inside the castle. I realised where I was, killed nobody, turned around and left, but thereafter the castle throne-room was locked against me until respawn. Apparently just going through the door counted as unauthorised entry and was enough to get me excluded fromt he place.