Brad Justice (let me say that again, Brad Justice!) sent us a valuable tip about Titan Panel, and it's easily confirmed by a casual look over at the official forums. Let me explain. No, there is too much -- let me sum up.
If you use Titan Panel, you may see an unexplainable GM ticket open in the upper right corner of your screen. You may open that empty ticket, and then Abandon it. Your attempt will fail. But don't worry -- it's not your fault. It's Titan Panel. That ticket will linger there like some kind of horrific nightmare. But there's hope.
You can either simply disable the AddOn until they get the problem sorted out or attempt a "full UI reset." (A full UI reset is the process by which you basically delete the WTF folder, Cache, and Interface folders and more or less start all over again.) I personally went for the slightly less-intense "disable" option.
Anyway, good luck fixing it -- we just wanted to let you know this is what's up, since Titan Panel's pretty popular.
Edit: With a ninja-like quickness, Titan Panel has released an update which should help clear this up.