Okay, I have tried to find out why I have been receiving the "Unknown Error (11111)" when trying to purchase anything from iTunes. I think I figured out the problem. Seeing how there are few threads with answers to this problem, I'll save you some time. If you have an account with AOL and you are using your ID to log in, make sure that everything is up to date with AOL such as your billing information, etc., for some odd reason, my information needed to be updated and it had been at least a month since my last log in. All I did was log in and update my AOL info and I tried to purchase from iTunes and VOILA, it worked!! Hope this helps...
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