We're excited to announce that we've fully migrated the Xbox Forums to their new home, here on the Microsoft Community forums!
As of today, going to forums.xbox.com will redirect you here to the Xbox area of the Community forums. We've moved all of your existing threads over so you can continue and start conversations with the new forums experience.
We sincerely appreciate the feedback you have provided over this transition and can't wait for you to check out the new Xbox Forums!
There's a thread about this exact same problem right below. Don't know of a fix but it's happen to a few of my buds (including me) and a few others. Me and my bud gave up, I wouldn't worry much about. The DLC's download on your hard drive anyway and playing
through the regular campaign didnt have many hiccups at all.