Contour DVR must be rebooted.

Our Contour DVR requires us to reboot several times per week. This happens when the TV screen will stop and the channel can not be changed. Upon reboot it will work fine for a day or so then again it happens. It is plugged into wall outlet and using upgraded cable installed by COX installer. We reboot using the help menu.

What's up with that and how do we fix it?