Presets Not Working

[Coach]

When I got in my car this morning my first three preset sat. stations refused to work. When I place my finger over the button my I-Drive screen displays the station, but when I push it won't work. My other three presets work fine and when I preset the three that did work over the the buttons that didn't work, they worked. So when I tried to set one of the stationg that wouldn't work(Alt. Nation) to one of the buttons that did work, it didn't work.

Anyone have a clue?
Coach