Hmmm, I had a similar issue the other day. I've had mine for almost a year now. The other day, I could not switch from the radio and the buttons were doing other actions instead of the actions they are supposed to do. For example, the button to open/close the face, would switch to my preset 1 station; preset 1 button was muting the radio; I could NOT change the mode so it made me really irate (cause I could not use the CarPC).
I basically reseted it by unplugging it from the battery for a good 10 minutes. This was about a month ago and have not seen any other issues. Unfortunately, never figured out what it was but it was definately weird! If you find the cause, let us know.