i just noticed mine does the same thing "sometimes",
if it's hot and the batteries are low,i hit a bump and it shuts off.i did some investigating and it seems the batteries are were not touching the metal tight.alot of the etrex's need adj.by the batteries cuz the same thing happened to my friend.
i pulled the metal tabs out a little safely,and have not had another problem.
My Garmin gps III would cut off on my dualsport. I read where you could put a strip of electrical tape down the side of the batteries it would reduce the vibration. Ive only tested it a few times but it seems to have worked,just makes the batteries a little harder to get in and out.
If a little is good,too much has got to be better.</p>
I spread out the battery contacts and it still died. I even carried it in my pocket and it croaked. ND, I agree with you that the batteries don't last as long in the heat. The Etrex battery meter must be wrong on mine as well. It shows half of a charged and it would shut down after about 10 seconds. Makes me mad. I'll try the electrical tape trick. Thanks guys.