In case you didn't know, firmware 1.01 for the X100 was released today. From Fujifilm:
The firmware update ver.1.01 incorporates the improvement against inadequate operation shown in the following.
If the images are shot with ISO Bracketing mode when "QUICK START MODE"(*1) is set to "ON" and turn off the camera,the camera cannot be turned on again even with ordinary operation.
*1 Menu of "QUICK START MODE" is set to "OFF" as factory-default value.
So it's a quick fix for a rare but nasty bug that could possibly brick the camera. Sources close to Fujifilm say there WILL be a more substantial update in the future to address some of the user feedback they've been hearing.