I'm assuming you're in the early update preview program?
If so this is a known issue over on the official preview forums, last I checked there were about six pages worth of people complaining about this issue myself included.
The most recent update is somehow causing this and apparently Microsoft is already working on a update/patch to resolve it
So no need to call Microsoft, just hope for a quick update!
Thank you! Went through 7 360s and I was starting to have flashbacks.
Yeah no problem, I think I'll be opting out of the preview program. Dealing with bugs in chat and in the software isn't a big deal but this affects the hardware and the game discs themselves, that's a no go for me