mbmw530i007

I have a 2008 528i with the Navigation, there are 6 buttons below the CD/DVD for storing radio stations of phone contacts. When I got the car, you could glide over the buttons and the bottom of the Navigation screen would light up with whatever was stored for those buttons.
Now, if I touch any of those buttons or hit the next track button or even mute the volume with the knob next to these buttons. The bottom of the Nav screen freezes with the contents of the buttons on the screen and that row doesn't go away until I reset the head unit or restart the car. I'm guessing some sensor has gone bad, any input would be greatly appreciated.