(Moved from another thread that no longer seems appropriate)
For the past few (couple?) weeks, my Premiere was having trouble getting channels, seemingly at random. It would try to record, but there would just be a blank screen and when the "recording" was done there would be nothing in Now Playing. At the same time, I also started having problems with extremely intermittent pixelization, drop-pouts, stutters, etc. Not constantly, but maybe a few little glitches each show.
Yesterday I got a Roamio, and since then it's been a nightmare. Frequent "Searching for channel" errors, frequent "Unauthorized" errors, frequent "Cannot get a signal" errors. If I jump from tuner to tuner, I can eventually get a channel to show up, and once I even managed to get all six tuners where I wanted them. But when I change channels, often I end up with an error again, and the problem sometimes cascades. Early in the Roamio process, they had me go to Comcast and swap out my CableCard, so now I have a new TiVo, and new CableCard, but similar problems (not identical; with the Premiere there was never an error message). At one point I was thinking I only had a certain number of functioning tuners, but that's apparently not the case since I did have six working at one point.