I know you may wonder why does Kitt start new threads? Does she have nothing else to do? LOL
A thread may be locked that is excessively long and difficult for forum members to navigate and read easily. When threads get long, they become paginated, which means that members have to click on a Page 2, or Page 3 link, etc. to see more posts in the thread. When posts get to 3 pages or more, it becomes a hassle to navigate and could be resolved by starting a new thread on the same topic. But some threads just won't die and can go on, and on, and on. Moderators may decide what threads are getting too long, but a good rule of thumb is any thread over 50 posts is a good candidate to be locked.
So now you know and I also try to remember to reference the links to the original threads fyi if you should be looking for something you may have posted or read in the past.
Take care and Happy Posting.