X20 What Happened?
It could be a software crash, or it could also be a battery situation: a battery meter is at best an estimate of power remaining, and if the power level is getting erratic it'll easily cause a crash.
I've had this with a Nikon and a Samsung.
I always buy two extra batteries on ebay, with a higher mAh rating than the originals, so I always have a spare, even if I forgot to recharge one. Always having one fully charged to swap when I get back is nice to have, and I've never seen the problem since.