Recently my Xperia X10i has started "crashing" and shutting down when attempting to take a picture or video.
The phone was working fine, and I don't recall doing any significant updates. It's always possible that an application updated in the background, though.
Still, the phone was working fine for quite a while, and for at least a month since my last application was installed.
First, the phone started to shut down whenever I tried to take a video using the built-in camera application. I chalked this up to some kind of bug between the camera app and CameraZoomFX, which I had tried but no longer used.
Next, it started to crash and shut down when taking a photo.
One time it began "crashing" and shutting down over and over. I began to restart it, over and over, and it would shut down over and over before I had a chance to see what was going on.
After four or five attempts, I noticed the battery indicator had dropped from 40% to less than 10% in those few restarts. I assumed the "crash" had left something active that should not have been.
After a bit I got a little suspicious of the crash theory. I uninstalled CameraZoomFX, but it did not help. Also, the unexpected shutdowns always seemed to occur when the battery was less than 50%.
Just recently the phone shut itself down without me trying to take a picture. The battery indicator was at 32%.
I realized then what was really going on - my battery is worn out. Plugging the unit in, I could not get it to shut down taking a picture or a video. The low-battery indicator was giving me bogus information.
I've got a new battery on order, we'll see if that fixes the problems.
So - if you start getting sudden and unexpected Android system shutdowns of your device, be sure to consider the battery. Given how these devices are used, 2 years for the battery will probably be a good lifetime.