Mine is doing the same thing, just started yesterday. I was able to get it to play using my Roku phone app but an error pops up about a minute into anything I try to watch. I can see and hear the program still playing behind the error overlay so the error itself is an error.
I did the "remove app" then "system restart" then "reinstall app" method recommended in a different thread and that did nothing.
I am upset. This leaves me in the ridiculous position of having to cast from my phone to watch TV on a Roku that is only two months old. It's absurd. CBS ALL ACCESS is one of my go-to apps and I need it to work.