Ok, so Ive had this strange issue with my mouse the past couple of days, and I think I just nailed it down to the "ProTimers" mod causing it. Here's the deal:

In the past 2-3 days since I had the addon (loaded it specifically for Ossirian, ctbossmod is unreliable at best), Ive been experiencing an occasional lack of responsiveness from my left or right mouse button in WoW. Every now and then my right mouse button would not register, and i would therefore not be able to mouselook to turn, or my left mouse button would not register my attempts at targetting. Also, very occasionally the game would cease to recognize what the mouse cursor was currently "over". Meaning I was hovering the cursor over a player, the Player Name target tooltip shows up etc, then promptly disappears as if nothing is under the cursor.

So there are the three strange issues. Has anyone experienced something like this before in general, or specifically with ProTimers? Obviously I can just not load protimers to fix my issue today, but, I'd rather be able to use it, as it has proved extremely helpful.

Lots of addons will have an invisible frame on your screen and forget to disable mouse input. Even CTRA's emergency monitor is guilty of this when hidden. Wherever it is on your screen, you cannot click or even mouse over things. If you find out which addon is causing it, you can either un-hide it and move it to a different part of your screen that you don't normally click on, or find a good place in the code to add:
Also don't forget to add this somewhere else, so you can actually access the addon when you want to:
Even the edges of the default UI's chat frames (the parts that you can drag to resize the frames) don't allow clicking through when hidden or locked. It's an oversight/limitation in a huge number of mods.

Cool, that makes sense, and I will try messing around with the invisible window, and possibly resizing it!