If you notice something is different with your Xbox today, you can blame a software upgrade.
The software update will happen to Internet enabled Xboxes the moment you turn them on, so for a short time they may not be functional.
The estimate is somewhere around 30 minutes, so you might not be able to get your game "fix" if you only have a short window of opportunity.
Microsoft is pushing through changes to the Xbox operating system.
Users don't have a choice. The upgrade is coming whether you like it or not.
It will change the appearance of the system's interface. It will also add several cool new features, like the ability to watch Netflix' movies-on-demand service, but only work if you are already a Netflix customer.
Here's a FAQ link with more information.