Few days ago I encountered a weird issue with my new Fujifilm x100s which I bought recently. I was quite upset, since the camera was brand new and I was not sure if it was just a bug in the firmware, or if something was wrong with the camera itself. A problem occurred when I tried to take some photos in macro mode through the electronic viewfinder. All of sudden the camera did not want to focus and became completely unresponsive and the warning message saying "turn off the camera and turn on again" appeared on the display.
It may sound strange, but the cause of the problem was the standard Hoya 49mm Skylight filter I put on my lens. After removing it everything worked like a charm.
I wanted to make a video describing the problem, but decided to post only photos this time. Hope you found this post useful. By the way, I still could not figure out whether this was the filter's wight or glass affecting the auto focus and causing the problem.
Thanks to +Karsa Papp's comment on my G+ stream I found the reason why this happened with this particular filter. While using the EvF focus extends more and it might hit the filter. To prevent this camera just shuts down. Using the adapter ring and then putting the filter solves the problem.