Sounds like you've got a dud GPS: Have you tried accessing the Garmin website and asking the obvious people on line: In my experience some one gets back to you PDQ.
I used to use a GPS 90 (son of 92) with the integral ariel and often in the depths of E Anglia lost the signal.
It didn't crash though: I merely carried on with the map and stopwatch till the signal came back.
[ If you've got to take the batteries out then you've got a major problem: most GPSs are designed to be idiot proof: hitting the keys in the wrong order isn't going to cause a major crash.]
Then when I got a 295, I used the suction ariel stuck to the windscreen (low wing Piper) and I've never lost the signal or had a freeze up.
Safe flying