I swear lol. I just came back to vote and play.BUT... era thought I came back to become a Game Master. Which I might add is ignorant, but hey, that's ERA! lol...
Try re-downloading Wow.. Putting the launcher in your WoW folder, Then make sure your on the right patch (4.3.4), also run the launcher as administrator.
This is where I download my WoW. http://www.joystiq.com/game/world-of-warcraft-wrath-of-the-lich-king/download/world-of-warcraft-full-install-client. Make sure to install all 3 starting with the first WoW. Then Burning Crusade, Then Lich.