Thanks! It worked. I changed my settings to not check spelling (I used another software before layout for that) and change the main language (document is a translation).
It was somehow hard to correct things, as I couldn't access or configure the Preflight settings while in document. Manage to set it while being in another document.
No more freeze and now I've got useful informations on things to check. Sorry for the inconvenience.
Nicolas "Gulix" Ronvel got a reaction from Jon P in Preflight crashes the application