I am having same problem ; problem started a few weeks ago. I think that Roku recently made changes to their Home screen and that is when this problem started for me. I cannot find a phone number for ROKU support,
Do you think Roku wants to hire techs to field your questions/problems? They would rather go the cheap route and have other users try to solve your issues... so no phone number and no company support. I am not going to buy another Roku and I'm not going to reboot every day.
Have a Sharp TV, samething happened. I pulled the plug, let it sit 10 minutes. Plugged it back in and ROKU started up normally. I think that while the video went black, me pushing buttons on the remote got me into some unknown position so the only fix was to shut it down entirely and restart it.