Re: Matrox G450 DualHead and mga_hal module
had the same problem - tried several things, but it seems that after
copying files mga_drv.so and mga_hal_drv.so from matrox site to /usr/
lib/xorg/modules/drivers (the first one replaces the existing file
with the same name in this directory) and adding
Option "IgnoreABI" "True"
to the X configuration file,
it seems to work for now...