I've had my Garmin Edge 305 for a little over a year, and it only spontaneously turned off on me once. It was during the Crater Lake Century, and I assume it was after I didn't avoid a decent sized pothole on a descent.
Now the calorie calculation is a complete mystery to me! Sometimes there's obvious errors, like the ride where I burned over 66,000 calories according to my Garmin.
Oh, that was the Crater Lake Ride, so I wonder if it has anything to do with the auto-shutoff "feature."
The calorie calculations from this weekend make me a little suspicious. On Saturday, I had a nice, 56 mile ride over flats and rolling hills. 2587 feet of elevation gain and 2194 calories burned. On Sunday, I had the Ride from He!! -- up Mt. Hamilton, then thru Mines Road to Livermore, where I baked in the heat and was beggin' for my mommy. 6616 feet of elevation gain with only 2993 calories burned. WHAT?!? Only 800 more calories burned than the pleasure cruise on Saturday?! I seriously doubt it.
I'll get back on the bike soon, I promise!