Very recently WoW stopped opening for me.  I click the icon, my CPU usage goes to 100% but the game never loads.  When I check task manager it says rundll32 is what's causing the high cpu usage.
Recently I installed "360 Total Security" with has a Game Booster mode.  I tried to exit the AV but still had the same problem.  After I uninstalled 360 Total Security and rebooted World of Warcraft opens fine again.