According to Xbox LIVE Service Status - Xbox.com
Xbox Music and Video
Users may experience difficulties with the following services:
- You won’t be able to browse, stream, download, or buy things at the Xbox Music and Video Store (also known as “Zune Marketplace”).
Affecting the following LIVE Platforms:
7/3/2013 11:15:07 AM PDT:Media lovers, are you having issues trying to access the Xbox Music and Video Marketplace from your phone or Windows 8 device? Don't worry; we'll get to the bottom of this! Our team is searching for possible solutions right this moment. Thanks for being patient while we work. We'll post another update in 30 minutes.