All the Centuras seem to do this, usually freeze up and restart while you're in the middle of something. 512MB RAM, with only 396 MB usable, isn't enough for an android phone unless you only call and text.
I know it isn't an answer, but there's a reason this "$100" phone went on a $25 sale during Black Friday sales last year if you ask me. I have one, I don't use it anymore, but it did the same thing. Two of my friends have one, they do the same thing. And people post here about it doing the same thing.