I didn't use the browser for the update!
I downloaded the archive "LS-series-fw160_fwwin.zip”, unpacked, launched the executable, and when it has finished, it said that it worked.
Now I've tried to reset to factory default but nothing has changed.... avi file are still unreachable from my SONY BRAVIA TV
I'm seriously thinking of downgrading the firmware to the previous stable version (1.57)