#9 - Nov. 10, 2010, 4:34 a.m.
In your case, Contemptment, it looks like your account was compromised and either you or the person who compromised the account created a new character on your realm. When your restoration was done and your characters/items were restored it brought the total number of characters on that realm above 10.
Since the new character was never logged in I deleted it so you shouldn't get this error any longer.