305 Elevation Problem

Sorry to have to break (no pun intended) this to you, but I have had two units do this. Once this problem starts eventually the Elevation field will display and stay at 65616. The problem is with the barometric altimeter and cannot be fixed without sending the unit to Garmin. When you call Garmin technical support, they will have you do all sorts of resets - be patient - eventually they will concede that the unit is busted and give you an RMA. Both times this happened was after the unit got a little roughed up (one time dropped it, the other time was mountain bike tumble) - evidently the altimeter is the least robust part. Good luck.