I've recently had XBox returned after a paid repair with MS, and figure it must be a refurbished model, as the firmware is several versions old. Unfortunately there appears to be an issue with the network connection. With my previous system, I didnt need to do anything other than connect it to my router, with this one, I had to set a permanent IP address, and now it's telling my I have an Insufficient MTU. This was not an issue with the system I sent away, nor is it an issue with my PS3. I've run through all of the guides and the issue remains.