I have the exact same problem for almost a year now that it is taking the fun of having an XT-1. Take a hundred shots and soon enough camera freezes just as described and the only way to get it back again is take the battery out. Even just by turning it on and leaving it on for 30secs freezes the camera. It had went thru various updates and is currently in version 4.21 and still has the same problem. With firmware 4.30 out am planning to update it but i have no hopes in solving the problem. I have the same hunch that it is the PWB too.
