Yeah, I'm waiting for the Windows Update stuff to finish, but I already have the K-Lite Mega Codec Pack and the Combined Community Codec Pack (needed that one for mkv files). I'll probably uninstall both my codec packs and the display driver, then reinstall 'em all and see if that helps. After Automatic Updates, anyway.
Edit: Well, I just tried uninstalling and reinstalling my display driver, but that didn't fix it, either. I know it was a Windows Update that did it, but I have no idea which one it was, since it was a batch install.
Re-Edit: O.o I just fixed it. I messed around in the display properties and got to the displays tab and changed the Scheme to Switch Amongst Displays and after I hit Alt+F5 (the hotkey for switching betwen displays), it worked all of a sudden. Well, hopefully, if anyone else gets this problem, this thread'll help 'em out.