Ok, here is the point :
Every lib and symlink seem to be correct. When I change everything without running sax2 and X, they remain correct. But when I want to start X, I have the error :
XIO: fatal IO error 104 (Connection reset by peer) on X server ":0.0"
after 0 requests (0 known processed) with 0 events remaining.
Even if I don't want to run glx (so impossible to run only with nvidia)
I'll try to look for some info about this...