On 9/29/2011 I received two emails stating that my Xbox Live account had been charged for a total of 6000G (70 dollars). Since I cancelled my Gold Subscription and my Xbox is basically a shelf-decoration now, I found this odd. I logged in to find my password had been changed as well. I recovered it, and now I can access my account as normal.
Suddenly I have THREE achievements in FIFA 12, a game I have never played, or thought about playing, because I hate sports. ALSO, ALL of the gamer points that were stolen were spent on Gold Premium Packs or some such for FIFA.
If I'm understanding this correctly, somebody got on my account, played FIFA, grabbed some DLC, and moved on.
It's currently 3 AM (I'm a night-owl) and I can't contact Xbox support, and I'm reading horror stories of peoples LIVE accounts being knocked out for months with zero accountability from Microsoft due to this very same issue. None of my other accounts on ANYTHING were compromised (I changed my passwords to be sure) so this HAS to be on LIVE's end.
I don't care about bricking my Xbox account, but I use Games For Windows Live (same LIVE account) to play Street Fighter IV: Arcade Edition, and if I'm denied my street fighting, I will go insane. I've removed the card in question from the account. Contacting the credit card company at the crack of dawn, and calling Xbox support. I hope I have a better experience than others have reported with this same problem.