I'm guessing many of the private channels are no longer supported. It's been my experience that it's not unusual for a firmware update to come out that breaks something in one of my channels (see my post about audio status messages in the Roku2 for an example). The content the channel links to could change over time as well requiring an update to the channel. All the channels probably worked when they first came out, but if the developer isn't still around to support the channel it's going to fall by the wayside. Unfortunately, it happens to public channels in the Channel Store as well.
-JT
