my roku3 is up2date, but while watching a program I am constantly getting the grey screen of death, wording across it say: unauthorized user & then black screen & buzzing sound.... restart roku generally helps but not always...
it is ethernet connected, excellent speed...

whats the solution?

Are you sure it's saying unauthorized user?

How many people are using your Netflix account? If there's only one that you know of, then I'd change your Netflix login as soon as possible, and I believe there's an option on the Netflix settings webpage to clear all current connections to your account too.

Here is how to keep unauthorized users away from your Netflix account.
Open 'Netflix' Open the Netflix website by clicking here. ...
Head Over to 'Recent Device Streaming Activity' ...
Change Your Netflix 'Password' ...
Chose to 'Sign Out' of All Devices.

This type of message can also be caused by a bad HDMI cable or HDMI port on your TV. I'd recommend changing the HDMI cable being used with your device, or connecting the device to a different HDMI port on the TV. See more here: https://support.roku.com/article/208755468-what-should-i-do-if-i-see-a-hdcp-error-detected-message-or-a-purple-screen-

Let us know how it goes from there! 


Cheers,
Tanner

I'm guessing it actually says "HDCP Unauthorized Content Disabled" or some such. RokuTanner has good recommendations to fix that.