I had the same issue with my XH2, after installing firmware V4.0. I tried different SD card, OEM battery and use Fuji lens. Nothing worked. So, I submitted a repair request on Fuji site and I sent the camera back to Fuji, they reverted my camera back to firmware 3.1 on my camera. It has been working fine without locking during my last few photo shoots. I learned the hard way to update firmware too soon, because I wanted better auto focus. If my camera is stable and I am generally happy with it, then I will wait for quite a while and check the web for stability issue, before upgrading firmware next time. You can help the next Fuji firmware release if you save the lock up setting in one of custom mode dial such as C7, before you send your camera for repair. Try call Fuji support, to see if they can make a special arrangement to revert back to firmware 3.1 without you sending your camera in.
