I know why my x1 freezes
It may not be the only reason why Xperias freeze but I have finally isolated the reason why mine has to be soft-reset every few hours - I just have to keep it warm!
If I leave it somewhere warm overnight it never freezes. If I leave it out on a table top, it will have frozen by the morning. If I carry it close to me in a jeans pocket it will be fine. If I put it on a belt hook, open to the cold, it will freeze. Now at least I can use it fairly normally and am enjoying this phone for the first time in weeks. By the way, I live in Hong Kong which is fairly warm anyway, so I would hate to think how this phone would perform somewhere colder.
Although I have a workaround now, I would be grateful if anyone knows what I can do about it. Do you think getting a new battery would help? I am bored of going back to the SE shop who repeatedly tell me nothing is wrong.