I get a message on the HD science channel 1153 "the channel you were watching has expired" or something similar to that and weird music that plays. We have gone through every setting and there isn't one that matches this for me to stop this from happening.
What you're describing sounds like a switched digital video channel timing out. These channels stop broadcasting 4 hours after the last viewer tunes in. This occurs at the network level so there is no setting in the box that will affect it. If you're still watching you'll see a prompt asking you to push select to confirm you're still there.