You should always use "X -configure" to generate a template xorg.conf file, taking some example off the Internet and adapting it to your needs is bound to cause issues.
Anyway, don't specify Vert/Horiz values.. your monitor has DDC functionality.
Right, So:
# X -configure
# $EDITOR xorg.conf.new
# mv xorg.conf.new /etc/X11/xorg.conf
That's all.. post back if you have any more problems.