had the same problem, with an HCx. I suspected storage in my garage in the summer in a high heat condition. (kept it in my bike handlebar bag so it was ready to go) . the Garmin rep I talked to said heat was a likely culprit, that people shouldn't leave them in the car ( this about a machine made to give turn by turn direction? what are you supposed to do with it when you go the the movie, take it in?) Anyway, the fix for me was to go back to REI and ask about getting some help regarding warranty, instead they just handed me a new unit and exchanged, no questions asked. If you have an REI in your area, it is like having a lifetime warranty on anything you buy. They don't have the lowest prices in town, but who cares if it ends up you got two for one if it breaks after the factory warranty is gone??