I regularly have this issue when trying to watch Netflix. It only happens on my TiVo box and not via any other device. My other apps work fine on the TiVo box. It's frustrating as it has happened as long as I've had the box but seems to be more regularly now. I have not been able to watch Netflix through the TiVo for a few days now. Powered off at the wall and still no joy.
Previously it just seemed to take the box 20 minutes to wake up properly and trying again later would work but not anymore, and to be honest that isn't a solution.