Switching from Fast to Normal did not make the flash work on the S110. I also did as you suggested and set CHDK back to default but that didn't make the flash work either.
If I don't use CHDK at all, the flash functions as normal.
If I start up with CHDK, go to normal mode, no [alt] at the bottom of the screen, the flash works.
If I startup with CHDK, the [alt] visible at the bottom, and I try your MDFB with the flash it won't work, forced or not, and also after that, if I go back to normal, no [alt] at the bottom, the flash won't work there either until I restart the camera.
Any ideas as I use it a lot with MDFB and birdies as I do with the S100. Thanks.