you can set your DVR to "power on" to any channel you want. or set it to turn on to the last channel you were watching. press the big blue COX button on the remote and you will find the setting. there is a DVR owners manual available online that I use when I am having problems. you didn't say what DVR you are using.
We can send a signal to the box that would reset your current settings back to default to see if that helps. If you would like us to do so, please send us an email and advise when would be the best time to do so. Also, include your account details to allow us access your information.