Why does my on-screen program Guide show "????" when I tune to a channel on the Guide?
If you attempt to tune to a channel that doesn’t exist, the on-screen program Guide may display “????” instead of a channel number. You can set the Guide to tune to the next highest channel by following these steps:
Press the SETTINGS button on your remote.
Using the LEFT/RIGHT arrow buttons, highlight HIGH DEFINITION.
Using the UP/DOWN arrow buttons, highlight Nearest Tune.