Thanks for offering, but it was really me you know, messing up with too many settings resulting in a blinking screen with "15 sec f8", and no way to get out of it, nor to take a picture.
So I erased the sd card and re-installed CHDK.
I try to carefully understand the features, while my batteries are frying at high speed rate, about 40 pics taken and they died. Is this normal?
Another humble question : when I activate override aperture (to get f11), I don't see it working - meaning there is no mention of the f11 aperture on screen. Tried to find the right way to get it on the forum, didn't find it...
Anyway, I managed to work some RAW files yet and I'm very pleased with the results.
Cheers,
JimNick