No lock ups on my Roamio Plus (yet- knock on wood), but I did have the channel problem. I would get that message that I wasn't authorized to receive channel. Crazy thing was, I was having no problem on one tuner, but all the others were. It was especially happening on the premium channels , HBO, etc.
When I got the tivo, I went through and set everything up prior to calling and switching my cable card over from my old unit (no TA needed here). What ended up fixing the problem for me was pulling out the card (while the unit was on), putting it back in, waited for it to be recognized, re-ran the guided setup, rebooted the unit and when it came back on...no problems. I'm thinking that maybe somehow it recognizes something on the card during the guided setup that it didn't the first time I did it without the card in. Who knows, but its worked perfectly since then. Been running it for 2 days now.