You'll need to manually edit your /etc/X11/xorg.conf file.
First, make a backup of the original:
(note the Capital X)
sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.bak
From a terminal, you can edit the original with root priveleges:
There might be next to nothing inside, but don't worry.
gksudo gedit /etc/X11/xorg.conf
The specs for your monitor were found, and I suggest adding these lines to your xorg.conf:
Be mindful of what lines need start and end-quotes, and those line that don't need quotes.
Identifier "Configured Monitor"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
Viewport 0 0
Save the file, quit the editor, and then use the logout function to restart X. Or you could just restart the computer. There are other ways to do this, but as a start, this is easiest.
Let us know how it goes!