Contour seizes up

Why does Contour keep freezing up?  It just stops working, cannot change channels or exit.  Eventually an error message comes up there is difficulty accessing this channel try again later but the message cannot be turned off without killing power to everything and restarting only for it to happen again a few minutes later.  This is a recurring problem, technicians have been out to the house and cannot find any issues with connections, the box, internet, router, modem etc.  Cox needs to lower their prices or provide quality service.