Certainly sounds like the box is faulty, possibly overheating, does it get hot, it could be that the vent underneath is blocked or the fan is faulty, if not blocked then you need to call Virgin on 150 from a Virgin phone, mobile or landline, or 0345 454 1111 from any other phone to report a fault, or wait here for one of the forum team team to pick this up which might be 2 to 3 day's.