[NTG-context] Strange format error with xetex engine on debian sid

Hi everyone, I'm experiencing problems with the xetex engine on debian sid. I'm using the official packages context and texlive-xetex. Maybe one of you has the same setup and has a hint... When I try to compile a simple "hello world!" document, I get the following message: This is XeTeXk, Version 3.141592-2.2-0.996-patch1 (Web2C 7.5.6) %&-line parsing enabled. ---! /var/lib/texmf/web2c/pdftex/cont-en.fmt was written by pdftex (Fatal format file error; I'm stymied) I didn't change anything to the setup made by official packages. Is there a problem with one of them? Best regards, Morgan