Search function crashing when language changes (using WPML plugin)

Hi – I'm working on http://papallaitants.fr/
The search box (in the left hand sidebar) works fine in French but if I try to change to English it crashes. I searched for cookies in French and got a link to the right place, then I changed to English and I get this link and a blank page.
http://papallaitants.fr/en//?s=cooki...x=6&submit.y=4

I've tried using widget logic for 2 separate search widgets but it makes no difference.

I made a video showing what is happening
http://youtu.be/BHZGJjcRgLw

It works fine in the default theme, is there something I've missed? Or will it never work in lovely Atahualpa? If not, is there a different way I can do it? HUGE thanks in advance for any help, it's the last bit of this tricky site to sort out.