I have had this happen after a software upgrade. Usually disconnecting the power from the back of the unit resolved it temporarily. If you have done an upgrade lately, you may want to re-install it to the unit again.
I received a update from Garmin with a fix for the problem, but it did not work tried a master reset which also did not work so I guess it will have to be sent off for repair here in Canada. (cannot be sent to Garmin in U.S.)
The unit is 9 month's old it has done about 20,000 mile about 16,000 of that on my wing.
It was in my van at the time I had used it to navigate to where I was, I left the van for about 30 minute's got back in and it just flashed STREETPILOT.
I have never had a problem with the unit and I do not think it was vibration.
I was picking my new wing up at the time (trailer -10c) perhap's it was upset at being made redundant!! LOL :lol: :lol:
P.S. it will never be redundant I will still use it on long journey's.