Xbox Live is currently experiencing issues which are affecting both the Purchasing of and usage of Content from the Xbox Live Marketplace, according to the Xbox Live Service Status page. The issues are affecting Xbox 360 along with Xbox on other devices.
Gamers may experience issues purchasing or changing your Gamertag from the Xbox Store, along with other content. Microsoft are aware of the problem and are hard at work on rectifying the issues.
All other aspects of Xbox Live are currently working fine, we will update you as soon as the status changes.