WoW: Issue with: Additional instances cannot be launched

Unable to enter instance? Me neither! How bad it is? Google the message and you get : ‘Results 1 – 10 of about 1,780,000 for Additional instances cannot be launched. (0.30 seconds)’ It was higher (over 2,000,000) but it seems Blizzard reps are deleting some messages about it (probably the...