There's a bug with VO that's causing it to divide by zero when trying to display info on the LCD of the Logitech G15 keyboards.
Until the update that fixes this is available, either stop using this keyboard or disable the LCD driver so VO won't try to display anything on it.

Rats! Is this why I crash on login ?

Yes it is, to answer my own question.

Fixed in patch 1.6.8.2.