Had a Garmin GPS like that a few years ago, same storey. Problem then was the Gulf War when the Americans scrambled all their satellites. Lost everything. After numerous calls and waits was told the same thing, reboot! After 6 tries I rebooted it alright, right into the alley. EVER SINCE I"VE BEEN THE CHAMP.
Have a Hummin Bird with no issues so far.
Funny thing was, kids got me another Garmin GPS for fathers day and I love it.